curl --request POST \
  --url https://api.atlas.kitchen/admin/v1/users/sync \
  --header 'Content-Type: application/json' \
  --header 'X-Api-Key: <api-key>' \
  --header 'X-Merchant-Id: <api-key>' \
  --data '
{
  "email": "<string>",
  "mobile_number": "<string>",
  "name": "<string>",
  "date_of_birth": "2023-12-25",
  "marketing_consent": true,
  "title": "<string>",
  "external_user_id": "<string>",
  "external_user_type": "<string>",
  "is_guest": true,
  "should_identify_guest": true
}
'

{
  "id": 123,
  "email": "<string>",
  "mobile_number": "<string>",
  "name": "<string>",
  "date_of_birth": "2023-12-25",
  "marketing_consent": true,
  "title": "<string>",
  "external_user_links": [
    {
      "external_user_id": "<string>",
      "external_user_type": "<string>"
    }
  ]
}