curl --request GET \
  --url https://your-instance.example.com/api/pipelines/stages/{stageId}/usage \
  --header 'Authorization: Bearer <token>'

{
  "success": true,
  "stageId": "67f0a0b0c0d0e0f0a0b0c0d0",
  "stageName": "New",
  "pipelineType": "Contact",
  "isInUse": true,
  "recordsCount": 7,
  "hasAlternatives": true,
  "alternatives": [
    {
      "id": "67f0a0b0c0d0e0f0a0b0c0d1",
      "name": "Qualified",
      "color": "#10B981"
    }
  ]
}