Redirect to the authenticated user's Stripe portal

Request

• Base URL
  https://openmercantil.es
• Auth
  API key in cookie ob_sess
• TypeScript
  https://skmtc.dev/openmercantil/apis/openmercantil-public-api/docs/api/v1/billing/portal/get.ts

  A function with typed inputs. Its response is checked against the schema.