removeAIOverlay method
Implementation
void removeAIOverlay(String id) {
_aiCaptions.removeWhere((c) => c.id == id);
_aiAudioTracks.removeWhere((t) => t.id == id);
_aiGeneratedClips.removeWhere((c) => c.id == id);
if (_selectedAIOverlayId == id) _selectedAIOverlayId = null;
}