Chat functionality is now fully handled by the Go backend (since v0.502).
Remove the deprecated Rust chat server and all its references from:
- CI/CD workflows (ci.yml, cd.yml, rust-ci.yml, chat-ci.yml)
- Monitoring & proxy config (prometheus, caddy, haproxy)
- Incus deployment scripts and documentation
- Monorepo config (package.json, dependabot, GH templates)
- HAProxy: route /hls to stream server
- Vite proxy: /ws, /stream, /hls for dev
- HLS_BASE_URL: empty when STREAM_URL relative (proxy)
- FEATURE_STATUS: HLS_STREAMING operational