Alterar assinatura existente com proration

curl -X POST "https://seu-dominio/billing/change-plan" \
  -H "Cookie: vertice_session=..." \
  -H "x-csrf-token: ..." \
  -H "content-type: application/json" \
  -d '{"plan":"business"}'

const response = await fetch('https://seu-dominio/billing/change-plan', {
  method: 'POST',
  headers: {
  credentials: 'include',
  'x-csrf-token': '<csrf-token>',
  'content-type': 'application/json',
  },
  body: JSON.stringify({
    "plan": "business"
  }),
});

const payload = await response.json();
console.log(payload);