insert method
Inserts a source at the specified index
Returns true if successful, false if the index is out of bounds
Implementation
bool insert(int index, AudioSource source) {
if (index < 0 || index > _sources.length) {
return false;
}
final newSources = List<AudioSource>.from(_sources);
newSources.insert(index, source);
// Adjust current index if necessary
if (index <= _currentIndex) {
_currentIndex++;
}
_updateSources(newSources);
return true;
}