Read passkey sign-in availability

Request

• Base URL
  https://api.stablesea.com (the document declares no server; this is the origin it was published from)
• Auth
  none declared
• TypeScript
  https://skmtc.dev/stablesea/apis/stable-sea-backend/docs/identity/sign_in/passkey_options/get.ts

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