curl --request GET \
  --url https://api.octolane.com/v1/contacts/fields \
  --header 'x-api-key: <api-key>'

{
  "success": true,
  "message": "<string>",
  "data": {
    "fields": [
      {
        "property_name": "customer_tier_123",
        "current_name": "Customer Tier",
        "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
        "attribute_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
        "original_name": "Customer Tier",
        "pipeline_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
        "is_editable": true,
        "is_hidden": true,
        "is_system": true,
        "attribute_order": 123,
        "metadata": {}
      }
    ]
  }
}