Added basic structure for game implementation

lib/data/dao/player_game_dao.dart

@@ -0,0 +1,40 @@
+import 'package:drift/drift.dart';
+import 'package:game_tracker/data/db/database.dart';
+import 'package:game_tracker/data/db/tables/player_game_table.dart';
+import 'package:game_tracker/data/dto/player.dart';
+
+part 'player_game_dao.g.dart';
+
+@DriftAccessor(tables: [PlayerGameTable])
+class PlayerGameDao extends DatabaseAccessor<AppDatabase>
+    with _$PlayerGameDaoMixin {
+  PlayerGameDao(super.db);
+
+  /// Checks if there are any players associated with the given [gameId].
+  /// Returns `true` if there are players, otherwise `false`.
+  Future<bool> hasGamePlayers(String gameId) async {
+    final count =
+        await (selectOnly(playerGameTable)
+              ..where(playerGameTable.gameId.equals(gameId))
+              ..addColumns([playerGameTable.playerId.count()]))
+            .map((row) => row.read(playerGameTable.playerId.count()))
+            .getSingle();
+    return (count ?? 0) > 0;
+  }
+
+  /// Retrieves a list of [Player]s associated with the given [gameId].
+  /// Returns an empty list if no players are found.
+  Future<List<Player>> getPlayersByGameId(String gameId) async {
+    final result = await (select(
+      playerGameTable,
+    )..where((p) => p.gameId.equals(gameId))).get();
+
+    if (result.isEmpty) return <Player>[];
+
+    final futures = result.map(
+      (row) => db.playerDao.getPlayerById(row.playerId),
+    );
+    final players = await Future.wait(futures);
+    return players.whereType<Player>().toList();
+  }
+}