curl --request POST \
  --url https://backend.testeswaffle.org/referrals/register \
  --header 'Content-Type: application/json' \
  --data '{
    "email": "novo.usuario@exemplo.com",
    "referrer_id": "abc123xyz"
  }'

{
  "success": true,
  "data": {
    "user_id": "usr_123456789",
    "email": "novo.usuario@exemplo.com",
    "created_at": "2024-01-15T10:30:00Z"
  }
}