Download URL stores challenge.html

Artifact download serves challenge.html for download instead of the expected file.

The <a> tag for the download link on the artifact page (example) contains the download tag, which always triggers a download regardless of what the target is. So serving a HTML file will just download it.

Example:

<a rel="nofollow"
   href="/waldi/debian-cloud-images/-/jobs/8962226/artifacts/download" 
   data-testid="download-artifacts"
   download="">

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information