DOWNLOAD / VIEW a file:
   GET https://skale.dev/throway/<id>
   Images and text-like types (text, html, json, pdf, svg) render inline
   in a browser; other files download.
   For a bundle, GET https://skale.dev/throway/<id> serves index.html inline (browser)
   or the whole bundle as a zip (agents). GET https://skale.dev/throway/<id>/<file>
   serves one file.
   Append ?download=1 to force a download of any file or the bundle zip.