feat: integrate RollyPay payment provider (SBP via USDT)

Full integration following PayPear/SeverPay patterns:
- API client with X-API-Key + X-Nonce auth, HMAC-SHA256 webhook verification
- RollyPayPaymentMixin with create, webhook, finalize (all side effects), status check
- CRUD, model, migration (0059), PaymentMethod.ROLLYPAY enum
- Webhook endpoint, cabinet topup, bot handler
- Statuses: created, processing, paid, expired, canceled, chargeback
- Config: ROLLYPAY_ENABLED, ROLLYPAY_API_KEY, ROLLYPAY_SIGNING_SECRET, etc.

app/services/payment_service.py

@@ -35,6 +35,7 @@ from app.services.payment.freekassa import FreekassaPaymentMixin
 from app.services.payment.kassa_ai import KassaAiPaymentMixin
 from app.services.payment.paypear import PayPearPaymentMixin
 from app.services.payment.riopay import RioPayPaymentMixin
+from app.services.payment.rollypay import RollyPayPaymentMixin
 from app.services.payment.severpay import SeverPayPaymentMixin
 from app.services.platega_service import PlategaService
 from app.services.wata_service import WataService
@@ -392,6 +393,7 @@ class PaymentService(
     RioPayPaymentMixin,
     SeverPayPaymentMixin,
     PayPearPaymentMixin,
+    RollyPayPaymentMixin,
 ):
     """Основной интерфейс платежей, делегирующий работу специализированным mixin-ам."""