P3: payments + payouts (multi-country adapter pattern, wallet-integrated)

- payments: cash instant + gateway intent/redirect + webhook confirm; topup credits wallet
- payouts: driver request (holds wallet.debit) + admin complete/fail (fail refunds)
- tables tripz_pay_payments / tripz_pay_payouts (logical payment schema, extractable later)
- providers: cash/cliq/zaincash/syriatel/mtn/shamcash/paymob/fawry (structure ready, creds later)
- migration InitPayments; wired into app.module

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/app.module.ts

@@ -24,6 +24,7 @@ import { RideTypesModule } from './modules/ride-types/ride-types.module';
 import { DispatchModule } from './modules/dispatch/dispatch.module';
 import { WalletModule } from './modules/wallet/wallet.module';
 import { NotificationsModule } from './modules/notifications/notifications.module';
+import { PaymentsModule } from './modules/payments/payments.module';
 
 @Module({
   imports: [
@@ -63,6 +64,7 @@ import { NotificationsModule } from './modules/notifications/notifications.modul
     RealtimeModule,
     FraudModule,
     WalletModule,
+    PaymentsModule,
     TripsModule,
     DispatchModule,
     ChatModule,