addAudioTrack method
Adds a single audio track (used by AI music/voiceover generation) and records the change in history.
Implementation
void addAudioTrack(VideoEditorAudioTrack track) {
audioController.addAudioTracks([track]);
audioController.selectAudio(track.id);
_selectedTrackType = VideoTrackType.audio;
_activeTrack = VideoTrackType.audio;
_error = null;
_saveState();
notifyListeners();
}