Renamed folder to "models"

lib/data/models/group.dart

@@ -0,0 +1,44 @@
+import 'package:clock/clock.dart';
+import 'package:tallee/data/models/player.dart';
+import 'package:uuid/uuid.dart';
+
+class Group {
+  final String id;
+  final String name;
+  final String description;
+  final DateTime createdAt;
+  final List<Player> members;
+
+  Group({
+    String? id,
+    DateTime? createdAt,
+    required this.name,
+    String? description,
+    required this.members,
+  }) : id = id ?? const Uuid().v4(),
+       createdAt = createdAt ?? clock.now(),
+       description = description ?? '';
+
+  @override
+  String toString() {
+    return 'Group{id: $id, name: $name, description: $description, members: $members}';
+  }
+
+  /// Creates a Group instance from a JSON object (memberIds format).
+  /// Player objects are reconstructed from memberIds by the DataTransferService.
+  Group.fromJson(Map<String, dynamic> json)
+    : id = json['id'],
+      createdAt = DateTime.parse(json['createdAt']),
+      name = json['name'],
+      description = json['description'],
+      members = []; // Populated during import via DataTransferService
+
+  /// Converts the Group instance to a JSON object using normalized format (memberIds only).
+  Map<String, dynamic> toJson() => {
+    'id': id,
+    'createdAt': createdAt.toIso8601String(),
+    'name': name,
+    'description': description,
+    'memberIds': members.map((member) => member.id).toList(),
+  };
+}