feat: add legacy msg response field

core/response.py

@@ -12,4 +12,9 @@ T = TypeVar("T")
 class APIResponse(BaseModel, Generic[T]):
     code: int = 200
     message: str = "ok"
+    msg: Optional[str] = None
     detail: Optional[T] = None
+
+    def model_post_init(self, __context) -> None:
+        if self.msg is None:
+            self.msg = self.message