curl --request POST \
  --url https://api.example.com/api/v1/open/objects/presign \
  --header 'Content-Type: application/json' \
  --header 'X-Api-Id: <x-api-id>' \
  --header 'X-Api-Nonce: <x-api-nonce>' \
  --header 'X-Api-Signature: <api-key>' \
  --header 'X-Api-Timestamp: <x-api-timestamp>' \
  --data '
{
  "bucket": "tenant-media",
  "object_key": "tenant_001/uploads/photo.jpg",
  "method": "PUT",
  "expires_seconds": 900,
  "content_type": "image/jpeg"
}
'

{
  "method": "PUT",
  "url": "https://objects.example.com/tenant-media/tenant_001/uploads/photo.jpg?signature=...",
  "headers": {
    "Content-Type": "image/jpeg"
  },
  "expires_at": "2026-04-22T12:15:00Z",
  "request_id": "req-001"
}