Integrate stream-start and stream-end signaling in worker.py and add /api/log/stream-start endpoint.

Optimize moderation logging: fix duplicate collisions, auto-refresh streamer OAuth tokens, and implement IRC keep-alive timeouts. Add unit tests.

feat: tune Whisper settings and add word mappings

fix: adjust Whisper parameters to disable temperature fallback and prevent hallucinations on silence/noise

feat: prepare transition to decoupled hosting (Render + Netlify + Supabase)