replaceTrack method
Replaces the media file of a track in place, keeping its timing.
Implementation
void replaceTrack(String id, File file, {Duration? duration}) {
final index = _audioTracks.indexWhere((a) => a.id == id);
if (index == -1) return;
_audioTracks[index] = _audioTracks[index].copyWith(
file: file,
duration: duration,
);
}