feat: at user

Signed-off-by: bggRGjQaUbCoE <githubaccount56556@proton.me>

lib/models_new/dynamic/dyn_mention/group.dart

@@ -0,0 +1,17 @@
+import 'package:PiliPlus/models_new/dynamic/dyn_mention/item.dart';
+
+class MentionGroup {
+  String? groupName;
+  int? groupType;
+  List<MentionItem>? items;
+
+  MentionGroup({this.groupName, this.groupType, this.items});
+
+  factory MentionGroup.fromJson(Map<String, dynamic> json) => MentionGroup(
+        groupName: json['group_name'] as String?,
+        groupType: json['group_type'] as int?,
+        items: (json['items'] as List<dynamic>?)
+            ?.map((e) => MentionItem.fromJson(e as Map<String, dynamic>))
+            .toList(),
+      );
+}