feat: throttle VOD resolution checks to 5m and auto-complete streams older than 3 hours with no VOD

feat: integrate automatic VOD ID resolution in chat_mod_worker.py

feat: smart gap detection and user roles sync backfill improvements

feat: worker and chat_mod_worker now also sync roles to /api/log/roles on every message batch

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

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