Extract the Soniox SRT/VTT cue grouping and rendering into a shared
litellm_core_utils/audio_utils/subtitle_utils module, have Gemini
transcription request word timestamps whenever response_format is srt or
vtt, and let the http handler rewrite the response text into the
synthesized subtitle document (dropping the internally requested words
array) for any provider config that opts in via
supports_subtitle_synthesis
Adds a Gemini audio transcription config that maps /v1/audio/transcriptions
onto the Interactions API (speaker attribution and word timestamps land on
the OpenAI verbose_json shape), registers both models with published pricing,
routes text-only Live sessions to TEXT responseModalities so
gemini-3.5-transcribe-live sessions survive, and makes the token-priced
transcription cost path provider-aware instead of hardcoding OpenAI.
