curl --request GET \
  --url https://zeus-api.agentspro.cn/api/knowledge-base/kb_abc123/documents/doc_xyz789 \
  --header 'Authorization: Bearer <token>'

{
  "id": "doc_xyz789",
  "fileName": "product-guide.pdf",
  "fileType": "application/pdf",
  "fileSize": 2048576,
  "status": "completed",
  "chunkCount": 45,
  "errorMessage": null,
  "createdAt": "2025-06-10T08:00:00Z"
}