agentra_authorize_paymentAuthorize PaymentRequest authorization for a payment to another agent or service. Agentra is NON-CUSTODIAL: this returns an authorization attestation and an unsigned transaction. Agentra never touches your private keys or moves your funds. YOU sign and submit the transaction yourself. Flow: (1) Call this endpoint -> (2) Receive unsigned tx + attestation -> (3) Sign with your Turnkey wallet -> (4) Submit to Base network -> (5) Call settle to record completion. If counterparty is unverified and require_counterparty_kya is true (default), you get a 402 challenge with instructions for the counterparty to onboard. This is Agentra's viral growth mechanism.