Disable script critic for music videos to preserve song timing

[pizzato]

Summary

The script critic could delete or reorder music-video scenes after their song windows were assigned. Final assembly still played the uninterrupted song, putting otherwise synchronized takes against the wrong audio. In “The Year I Forgot How to Fall,” critic deletions moved scene 3 ten seconds ahead of its intended song window.

Skip automatic script criticism for music videos, reject manual critic runs, and disable the critic controls in the editor. Update the documentation and automation setting text to describe the exception. The separate lyrics critic remains available before song generation.

This prevents new critic damage; it does not repair existing affected films.

Validation

• 208 tests passed across test_story_endpoints.py, test_automation_song.py, and test_performance_pathway.py, including regression coverage for skipped automatic passes and blocked manual runs preserving script/history.
• ruff check . and git diff --check passed.
• Frontend production build passed with npm run build -- --configLoader native.
• Browser verification confirmed the music-video critic button and pass selector are disabled with the timing explanation.