Add optional frpc deployment profile

- Add frpc/frpc.toml template for mapping the local Docker web entry on port 4002 to the public frps server.

- Add an optional Docker Compose frpc service behind the frpc profile, mounting the reusable frpc.toml configuration.

- Document how to enable the frpc profile, inspect frpc logs, and keep normal local startup unchanged.

- Clarify that public deployments should map only port 4002 and let Nginx Proxy Manager provide HTTPS for sstwbg.example.com instead of exposing 4443.

- Update Docker and deployment docs to match the reusable frpc workflow.

docker-compose.yaml

@@ -67,6 +67,21 @@ services:
       timeout: 5s
       retries: 6
 
+  frpc:
+    # XXX Optional public tunnel client. Edit frpc/frpc.toml before enabling this service.
+    image: snowdreamtech/frpc:latest
+    container_name: tuwen_frpc
+    restart: unless-stopped
+    network_mode: host
+    command: ["-c", "/etc/frp/frpc.toml"]
+    volumes:
+      - ./frpc/frpc.toml:/etc/frp/frpc.toml:ro
+    depends_on:
+      web:
+        condition: service_healthy
+    profiles:
+      - frpc
+
 volumes:
   postgres_data:
   uploads_data: