Add a full-screen update checker accessible from a button at the
bottom of the settings page. It queries the fork's GitHub latest
release and can download + install the APK in place.
- UpdateRepository (core/data): fetch releases/latest via GitHub API,
parse tag/description/APK asset, stream APK download to cacheDir
- VersionComparator (core/domain): compare 4.4.6-ba7opf.N style tags
(base version first, then build number; v-prefix tolerant) + tests
- IMainContainer/MainContainer: inject updateRepo
- UpdateCheckerScreen (feature/settings): shows current version,
checks for updates, displays latest version + release notes, and a
Download & install button; FileProvider hands the APK to the
system installer
- SettingsScreen: bottom entry button, full-screen page toggle
- AndroidManifest: REQUEST_INSTALL_PACKAGES permission + FileProvider
- i18n strings (en/zh)
