Add internal/updater package with UpdateService that queries the Gitea
generic-package API for newer releases, downloads the installer with
SHA256 verification, and launches it to apply the update. Includes
semver comparison (CompareVersions) and comprehensive test coverage
with httptest-based mock servers.
Wire UpdateService into WraithApp (app.go accepts version param) and
register as a Wails service in main.go. Frontend StatusBar shows a
blue pill notification when an update is available; SettingsModal About
section displays the current version and a "Check for Updates" button
with idle/checking/found/up-to-date/error states.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
