Upgrade to .NET 9 and Jellyfin 10.11 compatibility

[Copilot]

This PR updates the plugin to support .NET 9 and Jellyfin 10.11, addressing breaking API changes introduced in the latest Jellyfin release.

Changes

Framework and Dependencies

• Updated target framework from net8.0 to net9.0
• Updated Jellyfin.Controller from 10.9.9 to 10.11.0-rc8
• Updated Jellyfin.Model from 10.9.9 to 10.11.0-rc8
• Updated System.Net.Http.Json from 8.0.1 to 9.0.0 for .NET 9 compatibility
• Updated manifest script to target ABI 10.11.0.0
• Updated Makefile build output path to reference net9.0

Breaking API Changes in Jellyfin 10.11

User Entity Relocation

• The User entity has been moved from Jellyfin.Data.Entities to Jellyfin.Database.Implementations.Entities
• PermissionKind enum moved to Jellyfin.Database.Implementations.Enums
• The HasPermission method is now an extension method in Jellyfin.Data.UserEntityExtensions

Task Trigger API Changes

• TaskTriggerInfo.TriggerInterval constant replaced with TaskTriggerInfoType.IntervalTrigger enum value

Entity Query API Changes

• GetChildren(User, bool) method signature updated to require an InternalItemsQuery parameter
• Updated calls to GetChildren(_adminUser, true, new InternalItemsQuery())

Verification

The plugin builds successfully with .NET 9 and all compilation errors related to Jellyfin 10.11 breaking changes have been resolved. The changes are minimal and surgical, affecting only the necessary compatibility updates without altering the plugin's functionality.

Note

This update uses Jellyfin 10.11.0-rc8 (release candidate) as this is the latest available version. The plugin will be compatible with the stable 10.11 release once available.

Original prompt

Update the repository to use .NET 9 and ensure compatibility with Jellyfin version 10.11. This involves modifying the project files, dependencies, and any code updates required for the upgrade.

This pull request was created as a result of the following prompt from Copilot chat.

Update the repository to use .NET 9 and ensure compatibility with Jellyfin version 10.11. This involves modifying the project files, dependencies, and any code updates required for the upgrade.

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