refactor(apps): 主题系统迁移至 ColorScheme + 扩展架构并支持 Dark Mode

apps/lib/data/repositories/models/user_summary.dart

@@ -0,0 +1,19 @@
+class UserSummary {
+  final String id;
+  final String username;
+  final String? avatarUrl;
+
+  const UserSummary({
+    required this.id,
+    required this.username,
+    required this.avatarUrl,
+  });
+
+  factory UserSummary.fromJson(Map<String, dynamic> json) {
+    return UserSummary(
+      id: json['id'] as String,
+      username: json['username'] as String,
+      avatarUrl: json['avatar_url'] as String?,
+    );
+  }
+}