BFSAmvGuideBuilder builds the keyframes+blank guide for the AMV av2av LoRA:
auto_scene / manual_indices / external_images, with audio-beat placement
(librosa beat_track, RMS-onset fallback) to sync cuts to the music. Adds
librosa to requirements.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
