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

{
  "items": [
    {
      "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": {}
    }
  ],
  "hasMore": true,
  "nextCursor": "<string>"
}