page: Split empty-page placeholder messages into header and message

Following a new Figma frame that specifies larger text for the first
part:
  https://www.figma.com/design/1JTNtYo9memgW7vV6d0ygq/Zulip-Mobile?node-id=11194-18392&m=dev

The smaller text is left optional. The subscriptions page has a plan
to add that smaller text, as a TODO(#188); it's blocked on adding an
"All channels" page.

Author: chrisbobbe

assets/l10n/app_en.arb

@@ -793,10 +793,14 @@
   "@inboxPageTitle": {
     "description": "Title for the page with unreads."
   },
-  "inboxEmptyPlaceholder": "There are no unread messages in your inbox. Use the buttons below to view the combined feed or list of channels.",
-  "@inboxEmptyPlaceholder": {
+  "inboxEmptyPlaceholderHeader": "There are no unread messages in your inbox.",
+  "@inboxEmptyPlaceholderHeader": {
     "description": "Centered text on the 'Inbox' page saying that there is no content to show."
   },
+  "inboxEmptyPlaceholderMessage": "Use the buttons below to view the combined feed or list of channels.",
+  "@inboxEmptyPlaceholderMessage": {
+    "description": "Additional centered text on the 'Inbox' page saying that there is no content to show."
+  },
   "recentDmConversationsPageTitle": "Direct messages",
   "@recentDmConversationsPageTitle": {
     "description": "Title for the page with a list of DM conversations."
@@ -805,10 +809,14 @@
   "@recentDmConversationsSectionHeader": {
     "description": "Heading for direct messages section on the 'Inbox' message view."
   },
-  "recentDmConversationsEmptyPlaceholder": "You have no direct messages yet! Why not start the conversation?",
-  "@recentDmConversationsEmptyPlaceholder": {
+  "recentDmConversationsEmptyPlaceholderHeader": "You have no direct messages yet!",
+  "@recentDmConversationsEmptyPlaceholderHeader": {
     "description": "Centered text on the 'Direct messages' page saying that there is no content to show."
   },
+  "recentDmConversationsEmptyPlaceholderMessage": "Why not start the conversation?",
+  "@recentDmConversationsEmptyPlaceholderMessage": {
+    "description": "Additional centered text on the 'Direct messages' page saying that there is no content to show."
+  },
   "combinedFeedPageTitle": "Combined feed",
   "@combinedFeedPageTitle": {
     "description": "Page title for the 'Combined feed' message view."
@@ -825,8 +833,8 @@
   "@channelsPageTitle": {
     "description": "Title for the page with a list of subscribed channels."
   },
-  "channelsEmptyPlaceholder": "You are not subscribed to any channels yet.",
-  "@channelsEmptyPlaceholder": {
+  "channelsEmptyPlaceholderHeader": "You are not subscribed to any channels yet.",
+  "@channelsEmptyPlaceholderHeader": {
     "description": "Centered text on the 'Channels' page saying that there is no content to show."
   },
   "mainMenuMyProfile": "My profile",

lib/generated/l10n/zulip_localizations.dart

@@ -1206,8 +1206,14 @@ abstract class ZulipLocalizations {
   /// Centered text on the 'Inbox' page saying that there is no content to show.
   ///
   /// In en, this message translates to:
-  /// **'There are no unread messages in your inbox. Use the buttons below to view the combined feed or list of channels.'**
-  String get inboxEmptyPlaceholder;
+  /// **'There are no unread messages in your inbox.'**
+  String get inboxEmptyPlaceholderHeader;
+
+  /// Additional centered text on the 'Inbox' page saying that there is no content to show.
+  ///
+  /// In en, this message translates to:
+  /// **'Use the buttons below to view the combined feed or list of channels.'**
+  String get inboxEmptyPlaceholderMessage;
 
   /// Title for the page with a list of DM conversations.
   ///
@@ -1224,8 +1230,14 @@ abstract class ZulipLocalizations {
   /// Centered text on the 'Direct messages' page saying that there is no content to show.
   ///
   /// In en, this message translates to:
-  /// **'You have no direct messages yet! Why not start the conversation?'**
-  String get recentDmConversationsEmptyPlaceholder;
+  /// **'You have no direct messages yet!'**
+  String get recentDmConversationsEmptyPlaceholderHeader;
+
+  /// Additional centered text on the 'Direct messages' page saying that there is no content to show.
+  ///
+  /// In en, this message translates to:
+  /// **'Why not start the conversation?'**
+  String get recentDmConversationsEmptyPlaceholderMessage;
 
   /// Page title for the 'Combined feed' message view.
   ///
@@ -1255,7 +1267,7 @@ abstract class ZulipLocalizations {
   ///
   /// In en, this message translates to:
   /// **'You are not subscribed to any channels yet.'**
-  String get channelsEmptyPlaceholder;
+  String get channelsEmptyPlaceholderHeader;
 
   /// Label for main-menu button leading to the user's own profile.
   ///

lib/generated/l10n/zulip_localizations_ar.dart

@@ -651,8 +651,12 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   String get inboxPageTitle => 'Inbox';
 
   @override
-  String get inboxEmptyPlaceholder =>
-      'There are no unread messages in your inbox. Use the buttons below to view the combined feed or list of channels.';
+  String get inboxEmptyPlaceholderHeader =>
+      'There are no unread messages in your inbox.';
+
+  @override
+  String get inboxEmptyPlaceholderMessage =>
+      'Use the buttons below to view the combined feed or list of channels.';
 
   @override
   String get recentDmConversationsPageTitle => 'Direct messages';
@@ -661,8 +665,12 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   String get recentDmConversationsSectionHeader => 'Direct messages';
 
   @override
-  String get recentDmConversationsEmptyPlaceholder =>
-      'You have no direct messages yet! Why not start the conversation?';
+  String get recentDmConversationsEmptyPlaceholderHeader =>
+      'You have no direct messages yet!';
+
+  @override
+  String get recentDmConversationsEmptyPlaceholderMessage =>
+      'Why not start the conversation?';
 
   @override
   String get combinedFeedPageTitle => 'Combined feed';
@@ -677,7 +685,7 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   String get channelsPageTitle => 'Channels';
 
   @override
-  String get channelsEmptyPlaceholder =>
+  String get channelsEmptyPlaceholderHeader =>
       'You are not subscribed to any channels yet.';
 
   @override

lib/generated/l10n/zulip_localizations_de.dart

@@ -672,8 +672,12 @@ class ZulipLocalizationsDe extends ZulipLocalizations {
   String get inboxPageTitle => 'Eingang';
 
   @override
-  String get inboxEmptyPlaceholder =>
-      'Es sind keine ungelesenen Nachrichten in deinem Eingang. Verwende die Buttons unten um den kombinierten Feed oder die Kanalliste anzusehen.';
+  String get inboxEmptyPlaceholderHeader =>
+      'There are no unread messages in your inbox.';
+
+  @override
+  String get inboxEmptyPlaceholderMessage =>
+      'Use the buttons below to view the combined feed or list of channels.';
 
   @override
   String get recentDmConversationsPageTitle => 'Direktnachrichten';
@@ -682,8 +686,12 @@ class ZulipLocalizationsDe extends ZulipLocalizations {
   String get recentDmConversationsSectionHeader => 'Direktnachrichten';
 
   @override
-  String get recentDmConversationsEmptyPlaceholder =>
-      'Du hast noch keine Direktnachrichten! Warum nicht die Unterhaltung beginnen?';
+  String get recentDmConversationsEmptyPlaceholderHeader =>
+      'You have no direct messages yet!';
+
+  @override
+  String get recentDmConversationsEmptyPlaceholderMessage =>
+      'Why not start the conversation?';
 
   @override
   String get combinedFeedPageTitle => 'Kombinierter Feed';
@@ -698,7 +706,8 @@ class ZulipLocalizationsDe extends ZulipLocalizations {
   String get channelsPageTitle => 'Kanäle';
 
   @override
-  String get channelsEmptyPlaceholder => 'Du hast noch keine Kanäle abonniert.';
+  String get channelsEmptyPlaceholderHeader =>
+      'You are not subscribed to any channels yet.';
 
   @override
   String get mainMenuMyProfile => 'Mein Profil';

lib/generated/l10n/zulip_localizations_en.dart

@@ -651,8 +651,12 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   String get inboxPageTitle => 'Inbox';
 
   @override
-  String get inboxEmptyPlaceholder =>
-      'There are no unread messages in your inbox. Use the buttons below to view the combined feed or list of channels.';
+  String get inboxEmptyPlaceholderHeader =>
+      'There are no unread messages in your inbox.';
+
+  @override
+  String get inboxEmptyPlaceholderMessage =>
+      'Use the buttons below to view the combined feed or list of channels.';
 
   @override
   String get recentDmConversationsPageTitle => 'Direct messages';
@@ -661,8 +665,12 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   String get recentDmConversationsSectionHeader => 'Direct messages';
 
   @override
-  String get recentDmConversationsEmptyPlaceholder =>
-      'You have no direct messages yet! Why not start the conversation?';
+  String get recentDmConversationsEmptyPlaceholderHeader =>
+      'You have no direct messages yet!';
+
+  @override
+  String get recentDmConversationsEmptyPlaceholderMessage =>
+      'Why not start the conversation?';
 
   @override
   String get combinedFeedPageTitle => 'Combined feed';
@@ -677,7 +685,7 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   String get channelsPageTitle => 'Channels';
 
   @override
-  String get channelsEmptyPlaceholder =>
+  String get channelsEmptyPlaceholderHeader =>
       'You are not subscribed to any channels yet.';
 
   @override

lib/generated/l10n/zulip_localizations_it.dart

@@ -666,8 +666,12 @@ class ZulipLocalizationsIt extends ZulipLocalizations {
   String get inboxPageTitle => 'Inbox';
 
   @override
-  String get inboxEmptyPlaceholder =>
-      'Non ci sono messaggi non letti nella posta in arrivo. Usare i pulsanti sotto per visualizzare il feed combinato o l\'elenco dei canali.';
+  String get inboxEmptyPlaceholderHeader =>
+      'There are no unread messages in your inbox.';
+
+  @override
+  String get inboxEmptyPlaceholderMessage =>
+      'Use the buttons below to view the combined feed or list of channels.';
 
   @override
   String get recentDmConversationsPageTitle => 'Messaggi diretti';
@@ -676,8 +680,12 @@ class ZulipLocalizationsIt extends ZulipLocalizations {
   String get recentDmConversationsSectionHeader => 'Messaggi diretti';
 
   @override
-  String get recentDmConversationsEmptyPlaceholder =>
-      'Non ci sono ancora messaggi diretti! Perché non iniziare la conversazione?';
+  String get recentDmConversationsEmptyPlaceholderHeader =>
+      'You have no direct messages yet!';
+
+  @override
+  String get recentDmConversationsEmptyPlaceholderMessage =>
+      'Why not start the conversation?';
 
   @override
   String get combinedFeedPageTitle => 'Feed combinato';
@@ -692,8 +700,8 @@ class ZulipLocalizationsIt extends ZulipLocalizations {
   String get channelsPageTitle => 'Canali';
 
   @override
-  String get channelsEmptyPlaceholder =>
-      'Non sei ancora iscritto ad alcun canale.';
+  String get channelsEmptyPlaceholderHeader =>
+      'You are not subscribed to any channels yet.';
 
   @override
   String get mainMenuMyProfile => 'Il mio profilo';

lib/generated/l10n/zulip_localizations_ja.dart

@@ -651,8 +651,12 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   String get inboxPageTitle => 'Inbox';
 
   @override
-  String get inboxEmptyPlaceholder =>
-      'There are no unread messages in your inbox. Use the buttons below to view the combined feed or list of channels.';
+  String get inboxEmptyPlaceholderHeader =>
+      'There are no unread messages in your inbox.';
+
+  @override
+  String get inboxEmptyPlaceholderMessage =>
+      'Use the buttons below to view the combined feed or list of channels.';
 
   @override
   String get recentDmConversationsPageTitle => 'Direct messages';
@@ -661,8 +665,12 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   String get recentDmConversationsSectionHeader => 'Direct messages';
 
   @override
-  String get recentDmConversationsEmptyPlaceholder =>
-      'You have no direct messages yet! Why not start the conversation?';
+  String get recentDmConversationsEmptyPlaceholderHeader =>
+      'You have no direct messages yet!';
+
+  @override
+  String get recentDmConversationsEmptyPlaceholderMessage =>
+      'Why not start the conversation?';
 
   @override
   String get combinedFeedPageTitle => 'Combined feed';
@@ -677,7 +685,7 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   String get channelsPageTitle => 'Channels';
 
   @override
-  String get channelsEmptyPlaceholder =>
+  String get channelsEmptyPlaceholderHeader =>
       'You are not subscribed to any channels yet.';
 
   @override

lib/generated/l10n/zulip_localizations_nb.dart

@@ -651,8 +651,12 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   String get inboxPageTitle => 'Inbox';
 
   @override
-  String get inboxEmptyPlaceholder =>
-      'There are no unread messages in your inbox. Use the buttons below to view the combined feed or list of channels.';
+  String get inboxEmptyPlaceholderHeader =>
+      'There are no unread messages in your inbox.';
+
+  @override
+  String get inboxEmptyPlaceholderMessage =>
+      'Use the buttons below to view the combined feed or list of channels.';
 
   @override
   String get recentDmConversationsPageTitle => 'Direct messages';
@@ -661,8 +665,12 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   String get recentDmConversationsSectionHeader => 'Direct messages';
 
   @override
-  String get recentDmConversationsEmptyPlaceholder =>
-      'You have no direct messages yet! Why not start the conversation?';
+  String get recentDmConversationsEmptyPlaceholderHeader =>
+      'You have no direct messages yet!';
+
+  @override
+  String get recentDmConversationsEmptyPlaceholderMessage =>
+      'Why not start the conversation?';
 
   @override
   String get combinedFeedPageTitle => 'Combined feed';
@@ -677,7 +685,7 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   String get channelsPageTitle => 'Channels';
 
   @override
-  String get channelsEmptyPlaceholder =>
+  String get channelsEmptyPlaceholderHeader =>
       'You are not subscribed to any channels yet.';
 
   @override

lib/generated/l10n/zulip_localizations_pl.dart

@@ -662,8 +662,12 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   String get inboxPageTitle => 'Odebrane';
 
   @override
-  String get inboxEmptyPlaceholder =>
-      'Obecnie brak nowych wiadomości. Skorzystaj z przycisków u dołu ekranu aby przejść do widoku mieszanego lub listy kanałów.';
+  String get inboxEmptyPlaceholderHeader =>
+      'There are no unread messages in your inbox.';
+
+  @override
+  String get inboxEmptyPlaceholderMessage =>
+      'Use the buttons below to view the combined feed or list of channels.';
 
   @override
   String get recentDmConversationsPageTitle => 'Wiadomości bezpośrednie';
@@ -672,8 +676,12 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   String get recentDmConversationsSectionHeader => 'Wiadomości bezpośrednie';
 
   @override
-  String get recentDmConversationsEmptyPlaceholder =>
-      'Brak wiadomości w archiwum! Może warto rozpocząć dyskusję?';
+  String get recentDmConversationsEmptyPlaceholderHeader =>
+      'You have no direct messages yet!';
+
+  @override
+  String get recentDmConversationsEmptyPlaceholderMessage =>
+      'Why not start the conversation?';
 
   @override
   String get combinedFeedPageTitle => 'Mieszany widok';
@@ -688,7 +696,8 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   String get channelsPageTitle => 'Kanały';
 
   @override
-  String get channelsEmptyPlaceholder => 'Nie śledzisz żadnego z kanałów.';
+  String get channelsEmptyPlaceholderHeader =>
+      'You are not subscribed to any channels yet.';
 
   @override
   String get mainMenuMyProfile => 'Mój profil';