curl -X POST https://api.getagentdrive.com/v0/files/file_xyz789/presigned-url \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "expires_in": 7200
  }'

{
  "url": "https://storage.getagentdrive.com/files/file_xyz789?token=eyJhbGci...",
  "token": "eyJhbGci...",
  "expires_at": "2026-03-19T12:00:00Z"
}