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)

packages/server/src/routes/livekit.ts

@@ -55,10 +55,7 @@ export async function livekitRoutes(app: FastifyInstance): Promise<void> {
 
     const jwt = await token.toJwt();
 
-    const requestHost = request.headers.host?.replace(/:\d+$/, '') || '';
-    const livekitUrl = requestHost
-      ? `wss://${requestHost}/livekit`
-      : (config.livekit.url ?? '');
+    const livekitUrl = config.livekit.url ?? '';
 
     const response: LiveKitTokenResponse = {
       token: jwt,