back fix

mnemo_cards_backend/lib/database/daos/pack_dao.dart

@@ -22,8 +22,13 @@ class PackDao extends DatabaseAccessor<AppDatabase> with _$PackDaoMixin {
   // ==================== CardPacks ====================
 
   /// Получить пак по ID
-  Future<CardPack?> getPackById(String id) {
-    return (select(cardPacks)..where((p) => p.id.equals(id))).getSingleOrNull();
+  Future<CardPack?> getPackById(String id) async {
+    final query = select(cardPacks)
+      ..where((p) => p.id.equals(id))
+      ..limit(1);
+
+    final results = await query.get();
+    return results.isNotEmpty ? results.first : null;
   }
 
   /// Получить все паки

mnemo_cards_backend/lib/database/daos/payment_dao.dart

@@ -98,9 +98,13 @@ class PaymentDao extends DatabaseAccessor<AppDatabase>
   }
 
   /// Получить платеж по externalToken (только активные)
-  Future<Payment?> getPaymentByExternalToken(String token) {
-    return (selectActive()..where((p) => p.externalToken.equals(token)))
-        .getSingleOrNull();
+  Future<Payment?> getPaymentByExternalToken(String token) async {
+    final query = selectActive()
+      ..where((p) => p.externalToken.equals(token))
+      ..limit(1);
+
+    final results = await query.get();
+    return results.isNotEmpty ? results.first : null;
   }
 
   /// Получить платежи по продукту (store ID) (только активные)

mnemo_cards_backend/lib/database/daos/user_dao.dart

@@ -139,10 +139,13 @@ class UserDao extends DatabaseAccessor<AppDatabase> with _$UserDaoMixin {
   // ==================== UserData ====================
 
   /// Получить UserData пользователя
-  Future<UserData?> getUserData(String userId) {
-    return (select(
-      userDatas,
-    )..where((ud) => ud.userId.equals(userId))).getSingleOrNull();
+  Future<UserData?> getUserData(String userId) async {
+    final query = select(userDatas)
+      ..where((ud) => ud.userId.equals(userId))
+      ..limit(1);
+
+    final results = await query.get();
+    return results.isNotEmpty ? results.first : null;
   }
 
   /// Создать UserData