Fix : Web API tests by normalizing errors, validation, and uploads (#12620)

### What problem does this PR solve?

Fixes web API behavior mismatches that caused test failures by
normalizing error responses, tightening validations, correcting error
messages, and closing upload file handles.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

sdk/python/ragflow_sdk/ragflow.py

@@ -318,6 +318,8 @@ class RAGFlow:
         for data in res["data"]["memory_list"]:
             result_list.append(Memory(self, data))
         return {
+            "code": res.get("code", 0),
+            "message": res.get("message"),
             "memory_list": result_list,
             "total_count": res["data"]["total_count"]
         }