curl --request GET \
  --url https://api.heffl.com/api/v1/clients/{id} \
  --header 'x-api-key: <api-key>'

{
  "id": "<string>",
  "number": "<string>",
  "name": "<string>",
  "createdAt": "2023-11-07T05:31:56Z",
  "firstName": "<string>",
  "lastName": "<string>",
  "email": "<string>",
  "phone": "<string>",
  "website": "<string>",
  "stageId": "<string>",
  "customFields": {}
}