The .deb and .pkg.tar.zst are not signed packages, and the in-app
update prompt has users install them by hand, so nothing checked them.
A new checksums job hashes the Linux downloads into SHA256SUMS.txt,
signs it with the updater's minisign key (tauri signer) and uploads
SHA256SUMS.txt + SHA256SUMS.txt.minisig. The README shows the
verify-then-install command.
Refs #36
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5