配置 Nginx 反向代理和 Ngrok 内网穿透支持

- 添加 Nginx 反向代理配置（支持 ngrok 域名）
- 创建统一的 API 工具函数（自动适配域名）
- 更新前端 API 配置支持相对路径
- 配置支付宝回调地址使用 ngrok URL
- 优化 Docker Compose 配置（仅暴露 80 端口）
- 添加完整的部署和配置文档

demo/docker-compose.example.yml

@@ -0,0 +1,75 @@
+# 这是完整端口映射的示例配置
+# 用于开发环境或需要直接访问后端/数据库的场景
+
+services:
+  mysql:
+    image: mysql:8.0
+    container_name: demo-mysql
+    environment:
+      - MYSQL_ROOT_PASSWORD=177615
+      - MYSQL_DATABASE=aigc_platform
+      - MYSQL_USER=demo
+      - MYSQL_PASSWORD=demo_pass
+    ports:
+      - "3306:3306"  # 如果需要外部工具连接数据库
+    command: ["mysqld", "--character-set-server=utf8mb4", "--collation-server=utf8mb4_unicode_ci"]
+    volumes:
+      - mysql_data:/var/lib/mysql
+    healthcheck:
+      test: ["CMD", "mysqladmin", "ping", "-h", "localhost"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+    networks:
+      - app-network
+
+  backend:
+    build:
+      context: .
+      dockerfile: Dockerfile.backend
+    container_name: demo-backend
+    environment:
+      - SPRING_PROFILES_ACTIVE=prod
+      - DB_URL=jdbc:mysql://mysql:3306/aigc_platform?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true
+      - DB_USERNAME=demo
+      - DB_PASSWORD=demo_pass
+    depends_on:
+      mysql:
+        condition: service_healthy
+    ports:
+      - "8080:8080"  # 如果需要直接访问后端 API
+    volumes:
+      - uploads_data:/app/uploads
+    networks:
+      - app-network
+    healthcheck:
+      test: ["CMD-SHELL", "wget --no-verbose --tries=1 --spider http://localhost:8080/ || exit 1"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 60s
+
+  nginx:
+    build:
+      context: ./nginx
+      dockerfile: Dockerfile
+    container_name: demo-nginx
+    ports:
+      - "80:80"  # ✅ 内网穿透只需要这个端口
+    volumes:
+      - ./frontend/dist:/usr/share/nginx/html:ro
+      - ./nginx/nginx.conf:/etc/nginx/nginx.conf:ro
+    depends_on:
+      - backend
+    networks:
+      - app-network
+    restart: unless-stopped
+
+volumes:
+  mysql_data:
+  uploads_data:
+
+networks:
+  app-network:
+    driver: bridge
+