Creates a dynamic Pix: JSON with `oferta` (`pacote` with `usd`, or `saldo` with `centavos`) and the payer.

The payment releases what was bought by itself: the pack becomes the cred_… token already in the response; the balance goes to the logged-in account's organization. The first purchase needs documento (CPF or CNPJ, sent to the gateway and not stored here) and nome; email, pagina and navegador_id are optional. With forma: "cartao_boleto" the charge is open: the response brings pagamento_em, the gateway page where you pay by card, boleto or Pix (due in three days). With forma: "cartao" and cartao (titular, numero, mes, ano, cvv, documento, email, cep, numero_endereco, telefone), the charge is paid by card in the same request: 200 with estado: "pago", 202 with conferir while the issuer reviews it, 422 when the card is declined; the card is not stored. Set usd to an amount from pacotes or exatos in the GET response. The server sets the amount in cents and rejects amounts that the app has not declared. Returns: { id, credito, forma, pix, pagamento_em, estado, estado_em, cancelamento }