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

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

@@ -0,0 +1,63 @@
+enum FriendRequestStatus { pending, accepted, rejected }
+
+class FriendUser {
+  final String id;
+  final String username;
+  final String? avatarUrl;
+
+  const FriendUser({
+    required this.id,
+    required this.username,
+    required this.avatarUrl,
+  });
+
+  factory FriendUser.fromJson(Map<String, dynamic> json) {
+    return FriendUser(
+      id: json['id'] as String,
+      username: json['username'] as String,
+      avatarUrl: json['avatar_url'] as String?,
+    );
+  }
+}
+
+class FriendRequest {
+  final String id;
+  final FriendUser sender;
+  final FriendUser recipient;
+  final String? content;
+  final FriendRequestStatus status;
+  final DateTime createdAt;
+
+  const FriendRequest({
+    required this.id,
+    required this.sender,
+    required this.recipient,
+    required this.content,
+    required this.status,
+    required this.createdAt,
+  });
+
+  factory FriendRequest.fromJson(Map<String, dynamic> json) {
+    return FriendRequest(
+      id: json['id'] as String,
+      sender: FriendUser.fromJson(json['sender'] as Map<String, dynamic>),
+      recipient: FriendUser.fromJson(json['recipient'] as Map<String, dynamic>),
+      content: json['content'] as String?,
+      status: _friendRequestStatusFromApi(json['status'] as String),
+      createdAt: DateTime.parse(json['created_at'] as String),
+    );
+  }
+}
+
+FriendRequestStatus _friendRequestStatusFromApi(String raw) {
+  switch (raw) {
+    case 'pending':
+      return FriendRequestStatus.pending;
+    case 'accepted':
+      return FriendRequestStatus.accepted;
+    case 'rejected':
+      return FriendRequestStatus.rejected;
+    default:
+      throw StateError('Unsupported friend request status: $raw');
+  }
+}