Added updateGroupOfGame(), added docc & tests

lib/data/dao/game_dao.dart

@@ -65,6 +65,7 @@ class GameDao extends DatabaseAccessor<AppDatabase> with _$GameDaoMixin {
 
   /// Adds a new [Game] to the database.
   /// Also adds associated players and group if they exist.
+  /// If a game, player, or group already exists, it will be replaced.
   Future<void> addGame({required Game game}) async {
     await db.transaction(() async {
       await into(gameTable).insert(
@@ -89,11 +90,18 @@ class GameDao extends DatabaseAccessor<AppDatabase> with _$GameDaoMixin {
 
       if (game.group != null) {
         await db.groupDao.addGroup(group: game.group!);
-        await db.groupGameDao.addGroupToGame(game.id, game.group!.id);
+        await db.groupGameDao.addGroupToGame(
+          gameId: game.id,
+          groupId: game.group!.id,
+        );
       }
     });
   }
 
+  /// Adds multiple [Game]s to the database in a batch operation.
+  /// Also adds associated players and groups if they exist.
+  /// If the [games] list is empty, the method returns immediately.
+  /// If a game, player, or group already exists, it will be replaced.
   Future<void> addGames({required List<Game> games}) async {
     if (games.isEmpty) return;
     await db.transaction(() async {