Lightweight country list scoped to the countries Anton can deliver
payouts to. Use this to populate country dropdowns in an instrument-
creation form — paired with /v1/instruments/methods to build the
full method picker.
For the full reference catalog (including IS3 codes and currency
lists), use /v1/countries instead.
API keys are opaque strings prefixed by environment:
ak_live_* — production keys, accepted only on api.antonpayments.com.ak_test_* — sandbox keys, accepted only on api.antonpayments.dev.Include your key in the Authorization header: Bearer ak_test_....
Supported instrument countries.