curl --request GET \
  --url https://api.salescaptain.com/v1/list-custom-fields/{company_id} \
  --header 'Authorization: Bearer <token>'

{
  "message": "Custom fields fetched successfully!",
  "custom_fields": {
    "data": [
      {
        "cf_id": "d4e5f6a7-b8c9-0d1e-2f3a-4b5c6d7e8f9a",
        "cf_name": "industry",
        "cf_label": "Industry",
        "cf_datatype": "text",
        "cf_description": "Customer's industry sector",
        "created_at": "2024-01-10T09:00:00.000Z",
        "updated_at": "2024-01-15T11:30:00.000Z"
      },
      {
        "cf_id": "e5f6a7b8-c9d0-1e2f-3a4b-5c6d7e8f9a0b",
        "cf_name": "budget",
        "cf_label": "Budget",
        "cf_datatype": "number",
        "cf_description": "Customer's budget range",
        "created_at": "2024-01-12T14:00:00.000Z",
        "updated_at": null
      },
      {
        "cf_id": "f6a7b8c9-d0e1-2f3a-4b5c-6d7e8f9a0b1c",
        "cf_name": "company_size",
        "cf_label": "Company Size",
        "cf_datatype": "dropdown",
        "cf_description": "Number of employees",
        "created_at": "2024-01-20T10:15:00.000Z",
        "updated_at": "2024-02-01T08:45:00.000Z"
      }
    ]
  }
}