feat: all-in-one production deployment with install script

Redesign deployment as a single docker-compose with Backspace, Caddy
(auto-HTTPS), and LiveKit (voice/video) using hybrid networking:
Backspace+Caddy on isolated bridge, LiveKit on host mode for WebRTC.

- Add install.sh: interactive installer that handles Docker setup,
  domain/DNS verification, secret generation, LiveKit config, and
  deployment with health-check wait
- Add Caddyfile: static reverse proxy config using Caddy env vars,
  routes /livekit/* to host-mode LiveKit via host.docker.internal
- Rewrite docker-compose.yml: all-in-one with profiles (voice),
  no external volumes/networks, bind mount ./data for visibility
- Fix livekit.ts: use LIVEKIT_URL env var directly instead of
  Host-header derivation that made the env var dead code
- Fix Dockerfile: health check reads $PORT dynamically
- Update .env.example: add DOMAIN, COMPOSE_PROFILES documentation
- Update .gitignore: add livekit.yaml (contains secrets)

Dockerfile

@@ -75,9 +75,9 @@ ENV UPLOAD_DIR=/app/data/uploads
 
 EXPOSE 3000
 
-# Health check
-HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
-  CMD node -e "fetch('http://localhost:3000/api/health').then(r => r.ok ? process.exit(0) : process.exit(1)).catch(() => process.exit(1))"
+# Health check — reads PORT from environment so it works with any configured port
+HEALTHCHECK --interval=30s --timeout=5s --start-period=30s --retries=5 \
+  CMD node -e "fetch('http://localhost:' + (process.env.PORT || 3000) + '/api/health').then(r => r.ok ? process.exit(0) : process.exit(1)).catch(() => process.exit(1))"
 
 # Run the server using tsx from the server package directory
 WORKDIR /app/packages/server