refactor: 移除本地前端容器，仅保留远程部署

本地前端因 Casdoor OAuth 回调固定指向 onu.dhdx.fun，无法完成
登录流程，没有实际用途。转为仅远程服务器部署。

本地服务器现仅需 2 容器：backend + celery-worker(含beat)

Co-Authored-By: Claude <noreply@anthropic.com>

docker-compose.yml

@@ -27,16 +27,5 @@ services:
       backend:
         condition: service_healthy
 
-  frontend:
+  # frontend 仅在远程服务器部署，本地通过 docker-compose 不再启动
-    build: ./frontend
+  # 部署命令见 .claude/rules/07-remote-operations.md
-    ports:
-      - "18002:80"
-    restart: unless-stopped
-    depends_on:
-      backend:
-        condition: service_healthy
-    healthcheck:
-      test: ["CMD", "wget", "-qO-", "http://localhost:80/health"]
-      interval: 15s
-      timeout: 10s
-      retries: 5