Validate Challenge

curl --request POST \
  --url https://api.authsignal.com/v1/validate \
  --header 'Content-Type: application/json' \
  --data '{
  "token": "eyJhbGciOiJ..."
}'

{
  "isValid": true,
  "state": "CHALLENGE_SUCCEEDED",
  "stateUpdatedAt": "2023-11-07T05:31:56Z",
  "userId": "<string>",
  "action": "<string>",
  "idempotencyKey": "<string>",
  "verificationMethod": "SMS"
}