Set up Zoom support #219

Summary

Transcription in DNA is verified on Google Meet via the Vexa bot. Zoom is the other platform most studios run dailies on, and it is currently not supported: the Platform enum only has google_meet and teams (backend/src/dna/models/transcription.py), the frontend's parseMeetingUrl does not recognise zoom.us links, and the passcode field in the transcription menu has no platform that uses it. We should bring Zoom to the same level of support as Meet.

Details

• Goal - A user pastes a Zoom meeting link (with passcode if required), DNA dispatches a Vexa bot, and live segments flow into the playlist exactly as they do for Meet.
• Backend - Add ZOOM to Platform; confirm the Vexa provider's dispatch payload (platform, native_meeting_id, passcode) matches what Vexa expects for Zoom, and that status polling and transcript retrieval behave the same.
• Frontend - Extend parseMeetingUrl to handle Zoom URL shapes (zoom.us/j/<id>, vanity subdomains, ?pwd= in the link) and surface the passcode field only when the platform needs it.
• Vexa side - Zoom bots need Zoom app credentials configured on the Vexa deployment (cloud and self-hosted). Document what a studio must set up and how DNA surfaces a misconfiguration.
• Recording alignment - Zoom and Meet differ in how recording start time is derived for transcript/timecode alignment; verify the existing fallback path works end to end.
• Known unknowns - Waiting-room admission flow for the bot, breakout rooms, and whether Zoom's bot-name display matches what DNA sets.

Acceptance criteria

• zoom is a valid Platform across backend models, the Vexa provider, and the frontend types
• Pasting a Zoom link (with or without embedded passcode) dispatches a bot and shows live transcript segments in DNA
• Bot status (joining, waiting for admission, active, ended) is reported correctly for Zoom
• Zoom app credential setup for Vexa is documented in the backend README / QUICKSTART
• Tests cover Zoom URL parsing and the Zoom dispatch payload
• Google Meet and Teams behaviour is unchanged