feat: enhance chat service with Redis pub/sub for multi-instance message handling, add instance ID for deduplication

README.md

@@ -14,7 +14,7 @@
 
 The architecture (detailed in [`docs/architecture/README.md`](docs/architecture/README.md)) uses:
 
-- Hetzner Ashburn VPS for playout (FFmpeg + MediaMTX/SRS) and chat *(planned production; currently test lab at 192.168.88.40)*.
+- Hetzner Ashburn VPS for playout (FFmpeg + MediaMTX/SRS) and chat _(planned production; currently test lab at 192.168.88.40)_.
 - Cloudflare R2 + CDN with aggressive immutable caching of HLS `.ts` segments ($0 egress).
 - Lightweight static frontend and WebSocket chat backend.
 - Gitea self-hosted CI/CD (Actions) and Container Registry.