feat: add recurring transactions (Wiederkehrende Buchungen)

Lets treasurers/captains/coaches define recurring fee/levy dues that
are automatically booked for all active players on a monthly,
quarterly, or yearly schedule via a daily cron job, instead of having
to book them manually every cycle.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

myteamwallet_backend/src/recurring-transactions/dto/recurring-transaction-response.dto.ts

@@ -0,0 +1,12 @@
+import { RecurringTransactionIntervalEnum } from '../recurring-transaction-interval.enum';
+
+export class RecurringTransactionResponseDTO {
+  id: number;
+  description: string;
+  amount: number;
+  type: number;
+  interval: RecurringTransactionIntervalEnum;
+  nextRunDate: string;
+  active: boolean;
+  createdAt: Date;
+}