Circle init

const response = await fetch('https://api.bringyour.com/wallet/circle-init', {
    method: 'POST',
    headers: {
      "Authorization": "Bearer <token>"
    },
});
const data = await response.json();

{
  "user_token": {
    "user_token": "text",
    "encryption_key": "text"
  },
  "challenge_id": "text",
  "error": {
    "message": "text"
  }
}