## Pull request overview

This PR updates multi-clip paste operations in `TimelineDock` to better preserve transitions when copying/pasting a track/tractor, addressing a reported issue where pasted transitions could cause incorrect audio.

**Changes:**
- Detect transition “mix” clips in pasted MLT playlists and skip inserting them as normal clips.
- Recreate skipped transitions via `AddTransitionByTrimOutCommand` after inserting adjacent clips.
- Adjust inserted clip in/out points and insertion positions to account for skipped transition entries.

Comments suppressed due to low confidence (3)

**src/docks/timelinedock.cpp:4538**
* A transition is added whenever pendingTransitionDuration > 0, even if the transition tractor's right-side clip could not be resolved (pendingTransitionRightIn < 0 / pendingTransitionRightClip invalid) or does not match the current clip. In those cases this can add a transition between the wrong pair of clips. Gate the transition creation on successfully matching the current clip to the transition's right clip, but still reset the pending-transition state either way.
```
if (pendingTransitionDuration > 0) {
const int rightClipIndex = clipIndexAtPosition(trackIndex,
overwritePosition);
const int leftClipIndex = rightClipIndex - 1;
if (leftClipIndex >= 0 && rightClipIndex >= 0
```
**src/docks/timelinedock.cpp:4532**
* This code now overwrites clips at overwritePosition (= position + info.start - skippedTransitionDuration), but the group-restore pass later in this function still looks up overwritten clips using position + clipInfo.start. When transitions are skipped (skippedTransitionDuration > 0), those lookups can resolve to the wrong clip (or blank), causing copied group membership to be restored incorrectly for pastes that include transitions.
```
const int overwritePosition = position + info.start
- skippedTransitionDuration;
MAIN.undoStack()->push(new Timeline::OverwriteCommand(m_model,
trackIndex,
overwritePosition,
MLT.XML(&clip),
false));
```
**src/docks/timelinedock.cpp:4303**
* A transition is added whenever pendingTransitionDuration > 0, even if the transition tractor's right-side clip could not be resolved (pendingTransitionRightIn < 0 / pendingTransitionRightClip invalid) or does not match the current clip. In those cases this can add a transition between the wrong pair of clips. Gate the transition creation on successfully matching the current clip to the transition's right clip, but still reset the pending-transition state either way.
```
if (pendingTransitionDuration > 0) {
const int rightClipIndex = clipIndexAtPosition(trackIndex,
insertPosition);
const int leftClipIndex = rightClipIndex - 1;
if (leftClipIndex >= 0 && rightClipIndex >= 0
```