Merge remote-tracking branch 'origin/feature/29-timestamp-zu-allen-objekten-hinzufügen' into feature/31-json-import-fuer-testdaten

# Conflicts:
#	lib/data/dao/game_dao.dart
#	lib/data/db/database.g.dart
#	lib/data/db/tables/game_table.dart
#	lib/data/dto/game.dart
#	pubspec.yaml

lib/data/dto/group.dart

@@ -1,3 +1,4 @@
+import 'package:clock/clock.dart';
 import 'package:game_tracker/data/dto/player.dart';
 import 'package:uuid/uuid.dart';
 
@@ -5,9 +6,15 @@ class Group {
   final String id;
   final String name;
   final List<Player> members;
+  final DateTime createdAt;
 
-  Group({String? id, required this.name, required this.members})
-    : id = id ?? const Uuid().v4();
+  Group({
+    String? id,
+    DateTime? createdAt,
+    required this.name,
+    required this.members,
+  }) : id = id ?? const Uuid().v4(),
+       createdAt = createdAt ?? clock.now();
 
   @override
   String toString() {