Send a one-time code

Email the user a short code they can sign in with, instead of a password. They then send it to `POST /auth/login` as `otp`. This is how passwordless sign-in works, and it doubles as a way back in for a user who has forgotten their password. The answer is always the same, whether or not an account exists at that address, so this cannot be used to find out who has one. If the account belongs to a particular organization, include `organization_id`. No sign-in needed.

curl -X POST "https://api.dual.network/auth/otp" \  -H "Content-Type: application/json" \  -d '{    "email": "alex@example.com"  }'

{}

{
  "code": 3,
  "message": "Key: 'limit' Error:Field validation for 'limit' failed on the 'lte' tag"
}

{
  "code": 13,
  "message": "internal error"
}