Fix: Enforce 255-byte filename limit (#8290)

### What problem does this PR solve?

- Add filename length validation (<=255 bytes) for document
upload/rename in both HTTP and SDK APIs
- Update error messages for consistency
- Fix comparison operator in SDK from '>=' to '>' for filename length
check

### Type of change

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

api/apps/document_app.py

@@ -61,6 +61,8 @@ def upload():
     for file_obj in file_objs:
         if file_obj.filename == "":
             return get_json_result(data=False, message="No file selected!", code=settings.RetCode.ARGUMENT_ERROR)
+        if len(file_obj.filename.encode("utf-8")) > 255:
+            return get_json_result(data=False, message="File name must be 255 bytes or less.", code=settings.RetCode.ARGUMENT_ERROR)
 
     e, kb = KnowledgebaseService.get_by_id(kb_id)
     if not e:
@@ -147,6 +149,8 @@ def create():
     kb_id = req["kb_id"]
     if not kb_id:
         return get_json_result(data=False, message='Lack of "KB ID"', code=settings.RetCode.ARGUMENT_ERROR)
+    if len(req["name"].encode("utf-8")) > 255:
+        return get_json_result(data=False, message="File name must be 255 bytes or less.", code=settings.RetCode.ARGUMENT_ERROR)
 
     try:
         e, kb = KnowledgebaseService.get_by_id(kb_id)
@@ -402,6 +406,9 @@ def rename():
             return get_data_error_result(message="Document not found!")
         if pathlib.Path(req["name"].lower()).suffix != pathlib.Path(doc.name.lower()).suffix:
             return get_json_result(data=False, message="The extension of file can't be changed", code=settings.RetCode.ARGUMENT_ERROR)
+        if len(req["name"].encode("utf-8")) > 255:
+            return get_json_result(data=False, message="File name must be 255 bytes or less.", code=settings.RetCode.ARGUMENT_ERROR)
+
         for d in DocumentService.query(name=req["name"], kb_id=doc.kb_id):
             if d.name == req["name"]:
                 return get_data_error_result(message="Duplicated document name in the same knowledgebase.")