POST Cancel bulk contact job

POST /api/v1/contacts/bulk-jobs/{jobId}/cancel

{
  "data": {
    "id": "job_abc123",
    "operation": "add_to_group",
    "status": "cancelled",
    "requestedCount": 4900,
    "processedCount": 2550,
    "progress": 52,
    "groupId": "uuid-group",
    "summary": {
      "added": 2431,
      "alreadyInGroup": 91,
      "notFound": 28
    },
    "completedAt": "2026-05-08T10:00:09.000Z"
  }
}