refactor: optimize backend module

middleware/exception_handler.py

@@ -0,0 +1,11 @@
+from fastapi import Request, status
+from fastapi.responses import JSONResponse
+
+async def global_exception_handler(request: Request, exc: Exception):
+    """
+    全局异常处理
+    """
+    return JSONResponse(
+        status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+        content={"error": "Internal Server Error", "detail": str(exc)},
+    )