加入类型转换逻辑，防止解码失败

admin/dashboard/blueprints/message_push.py

@@ -541,12 +541,10 @@ def upload_file():
         file_type = 'video'
 
     if file and allowed_file(file.filename, file_type):
-        # 获取原始文件名和扩展名
-        original_filename = secure_filename(file.filename)
-        file_ext = original_filename.rsplit('.', 1)[1].lower()
-        
-        # 生成唯一文件名，保持原始扩展名
-        unique_filename = f"{uuid.uuid4().hex}.{file_ext}"
+        # 生成安全的文件名
+        filename = secure_filename(file.filename)
+        # 生成唯一文件名
+        unique_filename = f"{uuid.uuid4().hex}.{filename}"
 
         # 确保上传目录存在
         upload_folder = os.path.join(current_app.root_path, 'static', 'uploads')