Card payments with the test credentials are refused with 10111 and 10113,
which depend on the account behind the token. python -m
app.mercadopago_probe shows that account (and whether it is a test user),
the card methods it accepts, and how Mercado Pago classifies a card's first
digits: type, issuer and instalments. It creates and charges nothing.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
