Pick up credentials from the Secure Courier.
Completes the CREDENTIAL-DELIVERY flow (the ownership-proof
counterpart is ``receive_npub_proof``).
**Call this only after the user confirms they have replied.**
Deterministic, one-shot retrieval: name the response you want with
``(sender_npub, service, dpop_token)`` and the tool drains ONLY the
rendezvous relay that channel was pinned to. Every popped DM with the
wrong session phrase is deleted and its sender is NACK'd; the first DM
with the matching phrase is accepted (ACK'd) and the scan stops. If
none match, the queue is drained and a ``courier_not_found`` result is
returned. Do NOT poll, loop, or retry.
If a credential_card (ncred1...) is provided, it is redeemed directly
without any relay access (dpop_token not required for that path). On
success, the payment processor client is reinitialized from the new
credentials — no server restart needed.
ConnectorNo auth