Feat: Speichert Transaktions-Datumswerte in der korrekten UTC-Zone

lib/Repositories/transaction_repository.dart

@@ -9,16 +9,35 @@ class TransactionRepository {
 
   /// Fügt eine neue Transaktion zur Datenbank hinzu
   Future<Transaction?> add(final TransactionsCompanion transaction) async {
-    final int id = await _db.into(_db.transactions).insert(transaction);
+    final DateTime date = transaction.date.value!.add(
+      transaction.date.value!.timeZoneOffset,
+    );
+
+    final TransactionsCompanion transactionToAdd = TransactionsCompanion(
+      id: transaction.id,
+      name: transaction.name,
+      date: Value(date),
+      amount: transaction.amount,
+      checked: transaction.checked,
+      accountId: transaction.accountId,
+      recurringTransactionId: transaction.recurringTransactionId,
+      updatedAt: Value(DateTime.now()),
+    );
+
+    final int id = await _db.into(_db.transactions).insert(transactionToAdd);
     return find(id);
   }
 
   /// Aktualisiert eine Transaktion in der Datenbank
   Future<bool> update(final TransactionsCompanion transaction) {
+    final DateTime date = transaction.date.value!.add(
+      transaction.date.value!.timeZoneOffset,
+    );
+
     final TransactionsCompanion transactionToUpdate = TransactionsCompanion(
       id: transaction.id,
       name: transaction.name,
-      date: transaction.date,
+      date: Value(date),
       amount: transaction.amount,
       checked: transaction.checked,
       accountId: transaction.accountId,