get_invoice_payment_methods

Get how an invoice can be paid: a can:{} matrix (balance, card, swish, payson, autogiro), the unpaid total, the balance available, whether autogiro is enabled, and the saved cards:[{id, brand, last4}] masked to brand and last4 (never a pan or token). Call this before pay_invoice_with_card to pick a card_id. Reads only — to actually pay use pay_invoice_with_card, pay_invoice_with_balance, or pay_invoice_with_autogiro.