Initiate a cross-border payment via Tink's cross-border Payments API between two European markets

Steps

1. Verify the source institution and destination country combination is supported by calling GET /api/v1/providers and filtering by capability PAYMENT_INITIATION and checking for cross-border support in the provider's capabilities array
2. Authenticate the user and obtain an access_token with the payment:write scope for the source institution using the Tink Link authorization flow
3. POST /api/v1/payment-requests with sourceAccount (IBAN of debtor), destinationAccount (IBAN of beneficiary), amount (in minor units), currency (ISO 4217), remittanceInformation, and creditor name
4. Redirect the user to the payment authorization URL returned by Tink Link; the user authenticates via their bank's SCA flow (redirect or decoupled depending on the institution)
5. After authorization, poll GET /api/v1/payment-requests/{paymentRequestId}/payments until the payment reaches a terminal status (PENDING, INITIATED, or FAILED); INITIATED means the payment instruction was accepted by the bank but settlement is asynchronous
6. Handle EUR payments via SEPA Credit Transfer rules; cross-border payments within the SEPA zone must comply with the EU Instant Payments Regulation's expectation that all Eurozone PSPs support instant payments — check whether the receiving bank is instant-capable via the provider metadata