Waffo Payment Provider

将 waffoPaymentProvider() 放入 PaymentService.providers，配置 Merchant ID、Private Key、Product ID 与 webhook public key。

await city.payment.method("waffo").invoke({ topup_amount_minor: 500, idempotency_key: "order_123" });

支付确认后由 on_paid(record) 幂等发放 Primary Card Credits。