通知公告模块：修复新增通知bug，完善预览功能

supervision-admin/src/main/java/com/supervision/web/noticeManage/entity/Notice.java

@@ -11,4 +11,5 @@ public class Notice {
     private String attachment; // 存放前端传过来的文件URL
     private LocalDateTime createTime;
     private LocalDateTime updateTime;
+    private String fileType;
 }