video-transcribe now spells out the transcribe API job: send a video or
audio URL, then receive transcript text and timestamped chunks. An agent can
also pass a language hint or set task to translate for English text.
The response includes detected languages, source duration, the completed task,
and the source URL. The route accepts media up to 60 minutes or 500MB. Use
speaker-diarize when the next step needs speaker labels.