Fix cumulative character drift with original-take anchors and scene QA

[SubSchool]

Summary

• Anchor every character continuation to its first accepted take, with speech-aware private reference trimming.
• Add Gemini Pro audio-only voice review and per-scene identity/artifact/lip-sync review.
• Correct UGC on-camera versus voice-over direction and require a concrete cast bible.
• Scope partial regeneration explicitly, preserve old rendered versions, order mixed-role timelines correctly, and settle regeneration separately.
• Reserve extra paid regeneration takes before provider calls.

Verification

• Local editorial, renderer and pipeline tests passed, including corrupt-reference recovery and immutable renders.
• Web typecheck passed.
• New live QA correctly rejected a previously accepted degraded clip for voice drift, altered character appearance and disintegrating props.
• Production repair will replace only the requested later scenes and preserve the original release.