Create a PayTo agreement in Australia via Adyen's Checkout API and debit it for recurring payments

Verified steps

1. For a first/one-time payment, POST /payments with paymentMethod.type: payto and paymentMethod.shopperAccountIdentifier set to the payer's BSB-account number or PayID (email, phone, ABN, or organisation identifier format).
2. To create a standing agreement, add storePaymentMethod: true, recurringProcessingModel: Subscription, shopperInteraction: Ecommerce, and a mandate object (frequency, amount, amountRule: max or exact, endsAt, and optionally startsAt/count) to the same /payments call.
3. Expect action.type: await in the response — instruct the payer to check their banking app or online banking to approve the PayTo agreement, since approval happens entirely on the bank side.
4. Listen for the RECURRING_CONTRACT and recurring.token.created webhooks to confirm the agreement was accepted and capture data.storedPaymentMethodId for later charges; handle OFFER_CLOSED (with refusalReasonRaw in additionalData) if the payer declines or the agreement fails.
5. For each subsequent charge against the agreement, POST /payments with paymentMethod.type: payto, paymentMethod.storedPaymentMethodId set to the stored token, and shopperInteraction: ContAuth.