Refactor permission checks and decorators usage

Refactored permission checks in built-in plugins to use the new @require_permission decorator, improving code clarity and consistency. Enhanced permission_decorators to better extract ChatStream and support PlusCommand. Updated PermissionCommand to use permission decorators for all subcommands, improved user mention parsing, and improved feedback messages. Registered a new permission node for sending feeds in MaiZone plugin and updated command registration to use PlusCommand info.

src/plugin_system/base/command_args.py

@@ -50,7 +50,8 @@ class CommandArgs:
                     self._parsed_args = self._raw_args.split()
         
         return self._parsed_args
-    
+
+    @property
     def is_empty(self) -> bool:
         """检查参数是否为空
         
@@ -73,7 +74,8 @@ class CommandArgs:
         if 0 <= index < len(args):
             return args[index]
         return default
-    
+
+    @property
     def get_first(self, default: str = "") -> str:
         """获取第一个参数