修改幾個小 issue

lib/AnnouncementManager/announcement_model.dart

@@ -9,6 +9,7 @@ class Announcement {
   final DateTime startDate; // startdate
   final DateTime endDate; // end_date
   final String? attachment; // bbs_attach
+  final String personCName; // 姓名
 
   Announcement({
     required this.uniqueNo,
@@ -19,6 +20,7 @@ class Announcement {
     required this.startDate,
     required this.endDate,
     this.attachment,
+    required this.personCName,
   });
 
   // Factory 構造函數：從 API 返回的 JSON (Map) 創建 Announcement 物件
@@ -41,6 +43,7 @@ class Announcement {
       startDate: parseDate(json['startdate'])!,
       endDate: parseDate(json['end_date'])!,
       attachment: json['bbs_attach'] as String?,
+      personCName: json['personCName'] as String,
     );
   }