Issue a payout_write API key, the key type used to send recipient payouts.

The key is pinned to your tenant and to the merchantId you send, and is revocable on its own. expiresAt is required and must be no more than 90 days away. environment sets the key type: test gives a znz_pt_ key that sends sandbox payouts only, and live gives a znz_pl_ key that sends production payouts only.

The key works only on the payout endpoints (/v1/mcp/payouts and /v1/tenants/{tenantId}/recipient-payouts) and is refused everywhere else. The full key is shown once, in this response.

Available to tenant owners and admins, and to merchant users for their own merchant. A merchant user asking for another merchant gets a 404.