已完成用户APP首期功能开发

交付用户端首期页面、配套接口、后台资源及测试文档。用户APP构建、静态分析和三个管理后台构建通过；完整测试仍有2项失败，后端模型注释检查未通过，详见交付记录。

apps/user_app/lib/domain/models/message_center.dart

@@ -0,0 +1,54 @@
+// 功能描述：解析消息中心真实业务消息及分类计数；版本：1.0.0。
+class UserMessage {
+  const UserMessage({
+    required this.key,
+    required this.category,
+    required this.title,
+    required this.summary,
+    required this.statusText,
+    required this.target,
+    required this.targetIdentity,
+    required this.occurredAt,
+    required this.read,
+  });
+
+  factory UserMessage.fromJson(Map<String, dynamic> json) => UserMessage(
+    key: json['key']?.toString() ?? '',
+    category: json['category']?.toString() ?? '',
+    title: json['title']?.toString() ?? '',
+    summary: json['summary']?.toString() ?? '',
+    statusText: json['status_text']?.toString() ?? '',
+    target: json['target']?.toString() ?? '',
+    targetIdentity: json['target_identity']?.toString() ?? '',
+    occurredAt:
+        DateTime.tryParse(json['occurred_at']?.toString() ?? '') ??
+        DateTime.fromMillisecondsSinceEpoch(0),
+    read: json['read'] == true,
+  );
+
+  final String key, category, title, summary, statusText, target, targetIdentity;
+  final DateTime occurredAt;
+  final bool read;
+}
+
+class MessageCenterData {
+  const MessageCenterData({required this.items, required this.counts});
+  factory MessageCenterData.fromJson(Map<String, dynamic> json) {
+    final rawItems = json['items'] is List ? json['items'] as List<dynamic> : const <dynamic>[];
+    final rawCounts = json['counts'] is Map
+        ? Map<String, dynamic>.from(json['counts'] as Map<dynamic, dynamic>)
+        : const <String, dynamic>{};
+    return MessageCenterData(
+      items: List.unmodifiable(
+        rawItems.whereType<Map<dynamic, dynamic>>().map(
+          (item) => UserMessage.fromJson(Map<String, dynamic>.from(item)),
+        ),
+      ),
+      counts: Map.unmodifiable(
+        rawCounts.map((key, value) => MapEntry(key, value is num ? value.toInt() : 0)),
+      ),
+    );
+  }
+  final List<UserMessage> items;
+  final Map<String, int> counts;
+}