✨ feat(classroom): enhance message sender information

- add senderType field to Message interface to distinguish user types
- optimize senderId handling by converting to string type
- refine sender display logic by removing redundant senderId fallback

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

@@ -79,6 +79,7 @@ export interface Message {
   content: string;
   sender?: string;
   senderId?: string;
+  senderType?: UserType;
   timestamp: number;
   fileId?: number; // 用于图片消息的文件ID
 }
@@ -748,8 +749,8 @@ export const useClassroom = ({ user }:{ user : User }) => {
             const historyMessages: Message[] = historyData.data.map((msg) => ({
               type: msg.type,
               content: msg.type === 'image' && msg.file ? msg.file.fullUrl : msg.content,
-              sender: msg.senderName || msg.senderId || '',
-              senderId: msg.senderId || '',
+              sender: msg.senderName || '',
+              senderId: msg.senderId?.toString() || '',
               timestamp: msg.timestamp
             }));