refactor: 端口改为内部映射，通过 Nginx 反向代理访问

- docker-compose.test.yml: API 和 MongoDB 端口改为 expose（仅容器内部可见）
- webhook-server.js: 端口改为 19001，绑定 127.0.0.1（仅本机访问）
- 新增 deploy/nginx-test.conf Nginx 反向代理配置
  - API: miniapp-api-test.dxz99wyr.cn → miniapp-api_test:3001
  - Webhook: miniapp-api-test-webhook.dxz99wyr.cn/webhook → 127.0.0.1:19001
- 更新 setup.sh 和 README.md 文档

docker-compose.test.yml

@@ -5,8 +5,8 @@ services:
       dockerfile: Dockerfile
     container_name: miniapp-api_test
     restart: unless-stopped
-    ports:
-      - "3001:3001"
+    expose:
+      - "3001"
     environment:
       - PORT=3001
       - NODE_ENV=production
@@ -38,8 +38,8 @@ services:
     image: mongo:7.0
     container_name: miniapp-api_test-mongo
     restart: unless-stopped
-    ports:
-      - "27019:27017"
+    expose:
+      - "27017"
     volumes:
       - mongo_data_test:/data/db
     environment: