curl "https://api.crbtrack.com/api/v1/labels/CBECUSD123456789" \
  -H "X-API-Key: <YOUR_API_KEY>"

{
  "trackingNumber": "CBECUSD123456789",
  "labelUrl": "https://labels.crbtrack.com/CBECUSD123456789.pdf?token=abc123",
  "format": "PDF",
  "createdAt": "2024-12-21T10:30:00Z",
  "printCount": 1
}

{
  "success": false,
  "error": {
    "code": "LABEL_NOT_FOUND",
    "message": "No label found for this tracking number",
    "message_es": "No se encontró etiqueta para este número de seguimiento",
    "requestId": "req_abc123"
  }
}