Generate Passkey Registration Options

curl --request POST \
  --url https://api.authsignal.com/v1/client/user-authenticators/passkey/registration-options \
  --header 'Content-Type: application/json' \
  --data '{
  "username": "<string>",
  "displayName": "<string>"
}'

{
  "challengeId": "<string>",
  "options": {}
}