Installed apps now show an 'Update available' button (menu bar) and can
one-click install signed updates. Adds the Sparkle dependency, an
UpdaterManager wired into AppState, the menu-bar banner + 'Check for
Updates', and Info.plist SUFeedURL (https://grammagem.app/appcast.xml),
SUPublicEDKey, and scheduled background checks.
Build / release:
- build.sh embeds + rpaths Sparkle.framework; sign-app.sh signs it
inside-out (XPC services, Updater.app, Autoupdate, framework, then app)
for a valid, notarizable signature.
- release.sh stamps the version, builds, signs, notarizes, staples, zips,
and emits the EdDSA-signed appcast.xml to upload to grammagem.app.
- A hidden --update-selftest checks a feed headlessly (CI/build pipeline).
Verified: a v0.1.0 build detects a v0.2.0 update against a local signed
appcast (UPDATE_FOUND: 0.2.0); the signed app passes codesign --strict.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
