feat: 完成网关服务代码实现，支持 WebSocket 长连接与健康检查

backend/docker-compose.yml

@@ -0,0 +1,19 @@
+version: '3.8'
+
+services:
+  nginx:
+    image: nginx:1.25-alpine
+    ports:
+      - "80:80"
+    volumes:
+      - ./nginx/nginx.conf:/etc/nginx/nginx.conf:ro
+    depends_on:
+      - gateway
+
+  gateway:
+    build:
+      context: ./gateway
+    ports:
+      - "8080:8080"
+    environment:
+      - GO_ENV=production