feat: switch command entities to sdk

pkg/command/operators/help.py

@@ -2,14 +2,17 @@ from __future__ import annotations
 
 import typing
 
-from .. import operator, entities
+from .. import operator
+from langbot_plugin.api.entities.builtin.command import context as command_context
 
 
 @operator.operator_class(name='help', help='显示帮助', usage='!help\n!help <命令名称>')
 class HelpOperator(operator.CommandOperator):
-    async def execute(self, context: entities.ExecuteContext) -> typing.AsyncGenerator[entities.CommandReturn, None]:
+    async def execute(
+        self, context: command_context.ExecuteContext
+    ) -> typing.AsyncGenerator[command_context.CommandReturn, None]:
         help = 'LangBot - 大语言模型原生即时通信机器人平台\n链接：https://langbot.app'
 
         help += '\n发送命令 !cmd 可查看命令列表'
 
-        yield entities.CommandReturn(text=help)
+        yield command_context.CommandReturn(text=help)