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/app.module.ts

@@ -1,4 +1,5 @@
 import { Module } from '@nestjs/common';
+import { ScheduleModule } from '@nestjs/schedule';
 import { UsersModule } from './users/users.module';
 import { AuthModule } from './auth/auth.module';
 import databaseConfig from './config/database.config';
@@ -22,9 +23,11 @@ import { join } from 'path';
 import { LoggingModule } from './database/logging/logging.module';
 import { TranslateModule } from './translate/translate.module';
 import { PenaltyModule } from './penalty/penalty.module';
+import { RecurringTransactionsModule } from './recurring-transactions/recurring-transactions.module';
 
 @Module({
   imports: [
+    ScheduleModule.forRoot(),
     ConfigModule.forRoot({
       isGlobal: true,
       load: [databaseConfig, authConfig, appConfig, mailConfig],
@@ -55,6 +58,7 @@ import { PenaltyModule } from './penalty/penalty.module';
     LoggingModule,
     TranslateModule,
     PenaltyModule,
+    RecurringTransactionsModule,
   ],
   providers: [],
 })