Fix inc/dec duration command when used with dotted notes

Resolves: #28069

The inc/dec duration command used the input state duration as the
initial duration instead of the duration of the selected note.
This started causing issues because the input state duration is changed on
each selection change in NotationNoteInput::updateInputState() when the
"Apply accidentals, [...]" setting is set to "To previous not entered".

Author: juli27

src/engraving/dom/cmd.cpp

@@ -3295,18 +3295,17 @@ void Score::cmdIncDecDuration(int nSteps, bool stepDotted)
     ChordRest* cr = toChordRest(el);
 
     // if measure rest is selected as input, then the correct initialDuration will be the
-    // duration of the measure's time signature, else is just the input state's duration
-    TDuration initialDuration;
-    if (cr->durationType() == DurationType::V_MEASURE) {
+    // duration of the measure's time signature, else is just the ChordRest's duration
+    TDuration initialDuration = cr->durationType();
+    if (initialDuration == DurationType::V_MEASURE) {
         initialDuration = TDuration(cr->measure()->timesig(), true);
 
         if (initialDuration.fraction() < cr->measure()->timesig() && nSteps > 0) {
             // Duration already shortened by truncation; shorten one step less
             --nSteps;
         }
-    } else {
-        initialDuration = m_is.duration();
     }
+
     TDuration d = (nSteps != 0) ? initialDuration.shiftRetainDots(nSteps, stepDotted) : initialDuration;
     if (!d.isValid()) {
         return;