修改lastMsgChat类型

xim/models/chat.ts

+import { MessageType } from "@/customer-service/model";
+
 export interface Chat {
     id: number;
     org_id: string;
@@ -20,7 +22,7 @@ export interface Chat {
     biz_id: string;
     last_msg_sender: string;
     last_msg_content: string;
-    last_msg_type: string;
+    last_msg_type: MessageType;
     business_data: {
         model_name: string;
         obj_id: string;