refactor: client 和 system 直接导出，不再使用中间量

docs/api/motajs-client/index.md

@@ -2,12 +2,12 @@
 
 `@motajs/client` 包含多个模块：
 
--   [ClientBase](../motajs-client-base/)
+-   [`@motajs/client-base`](../motajs-client-base/)
 
 示例：
 
 ```ts
-import { ClientBase } from '@motajs/client';
+import { KeyCode } from '@motajs/client';
 
-const { ClientBase } = Mota.require('@motajs/client');
+const { KeyCOde } = Mota.require('@motajs/client');
 ```

docs/api/motajs-system/index.md

@@ -2,16 +2,16 @@
 
 包含两个模块：
 
--   [Action](../motajs-system-action/index.md)
--   [UI](../motajs-system-ui/index.md)
+-   [`@motajs/system-action`](../motajs-system-action/index.md)
+-   [`@motajs/system-ui`](../motajs-system-ui/index.md)
 
 ## 引入示例
 
 ```ts
-import { Action, UI } from '@motajs/system';
+import { gameKey, UIController } from '@motajs/system';
 
-Action.gameKey.register(...);
-const myController = new UI.UIController('my-controller');
+gameKey.register(...);
+const myController = new UIController('my-controller');
 ```
 
 等效于：