Issue refunds

Refund a payment and track the refund.

Refund all or part of a captured payment using the original payment intent.

1. Create the refund

   Call Create Refund with the payment_intent_id and the amount to return. Partial refunds are supported by passing an amount smaller than the original payment.

2. Track it

   Refunds progress through RECEIVED → PROCESSING → COMPLETED (or FAILED). Poll Refund Status with the refund_id, or use webhooks.