🐛 fix(classroom): 修复课堂中用户上下线提示频繁问题

- 注释掉用户上下线时的showMessage提示，避免课堂内频繁弹窗干扰教学
- 保留console.log用于调试，不影响正常教学体验

src/client/mobile/components/Classroom/useClassroom.ts

@@ -345,12 +345,12 @@ export const useClassroom = ({ user }:{ user : User }) => {
     showMessage('注册rtc事件监听')
 
     aliRtcEngine.current.on('remoteUserOnLineNotify', (userId: string) => {
-      showMessage(`用户 ${userId} 加入课堂`);
+      // showMessage(`用户 ${userId} 加入课堂`);
       console.log('用户上线通知:', userId);
     });
 
     aliRtcEngine.current.on('remoteUserOffLineNotify', (userId: string) => {
-      showMessage(`用户 ${userId} 离开课堂`);
+      // showMessage(`用户 ${userId} 离开课堂`);
       console.log('用户下线通知:', userId);
       removeRemoteVideo(userId, 'camera');
       removeRemoteVideo(userId, 'screen');