Fix: update pipeline/__init__.py to import MusicHighlightOrchestrator

Clean repo: remove v3 leftovers, update README for music-only v4

Remove leftover v3 file: training/hype_scorer_training.ipynb

Remove leftover v3 file: docs/TESTING_GUIDE.md

Remove leftover v3 file: space.yaml

Remove leftover v3 file: .gitattributes

Remove leftover v3 file: REQUIREMENTS_CHECKLIST.md

Remove leftover v3 file: PLAN.md

Rebuild as music-only highlight extractor: Whisper + Librosa, remove multi-modal stack

Initialize ShortSmith v4 - scene-anchored clip boundaries, bug fixes from v3

initial commit