fix: Flask服务默认端口改为80，简化Dockerfile CMD

修改内容：
- flask_server.py: 默认端口从5000改为80
- Dockerfile: CMD简化，无需指定--port参数

最终Dockerfile:
FROM index-base:latest
WORKDIR /app
...
EXPOSE 80
CMD ["python", "datasource/flask_server.py", "--host", "0.0.0.0"]

datasource/flask_server.py

@@ -752,7 +752,7 @@ if __name__ == '__main__':
     
     parser = argparse.ArgumentParser(description='Universal Data Fetcher API Server')
     parser.add_argument('--host', default='0.0.0.0', help='Host to bind')
-    parser.add_argument('--port', type=int, default=5000, help='Port to bind')
+    parser.add_argument('--port', type=int, default=80, help='Port to bind')
     parser.add_argument('--debug', action='store_true', help='Enable debug mode')
     
     args = parser.parse_args()