Platform-aware install kinds: Linux AppImage and macOS self-install in place;
Windows defers — the update downloads and verifies in the background, then the
NSIS installer runs only from the user-confirmed restart (Tauri's installer
launch exits the process, so it must never fire behind a silent auto-check).
Linux system packages stay notify-only.
The release workflow gains dispatch-gated unsigned macOS/Windows test bundles
signed with the same minisign key, and a separate desktop-test update channel:
latest.json stays Linux-only on every release, while an opt-in fixed
'desktop-test' prerelease hosts latest-desktop-test.json (monotonic version
guard) so Linux-only releases can never strand distributed test builds. Build
jobs check out the SHA the validation job resolved, closing the tag-move race.
Sparkle-parity self-update for the apps/linux companion: tauri-plugin-updater +
process, checked silently on launch and from a "Check for Updates" tray item /
manual trigger. AppImage installs download, verify the signed update, and wait
for a user-confirmed restart; package-managed (deb) installs get a release-page
notice instead of replacing files the system package manager owns. The
linux-app release workflow signs the AppImage and publishes a signed latest.json
manifest that the app verifies with the committed minisign public key.
