feat(payment): add refund and reversal functionality to payment gateways

- Implemented `refund` and `reverse` methods in `PaymentGatewayInterface`.
- Added `PaymentRefundResult` class to handle refund operation results.
- Enhanced `MockGateway` and `SepGateway` to support refund and reversal operations.
- Updated `PaymentManager` to include `refundPayment` and `reversePayment` methods for handling refunds and reversals in transactions.
- Modified `ClinicSubscriptionRepository` and `SubscriptionService` to manage subscriptions during refunds.
- Added admin API endpoints for processing refunds and reversals.
- Updated security headers to allow form actions to the sandbox environment.
- Documented the new refund and reversal features in the API documentation.

assets/admin/types/index.ts

@@ -118,6 +118,8 @@ export interface Payment {
     status: PaymentStatus;
     gateway: PaymentGateway;
     ref_id: string | null;
+    card_pan?: string | null;
+    refunds?: { amount: number; ref: string; at: number }[];
     patient_mobile: string;
     appointment_uuid: string | null;
     paid_at: string | null;