bug: non-critical app update check only gates the home screen

[ovitrif]

The non-critical app update timed sheet only evaluates on the home screen (TimedSheetManager.onHomeScreenEntered() called from HomeView.onAppear). It doesn't cover onboarding or other flows, so it can miss showing the update prompt on first launch.

Critical updates are already handled at the top level in AppScene, so they are not affected.

Suggestions

• The non-critical update check should also cover the onboarding flow (when no wallet is loaded), scoped at the highest level which includes all screens within the app
• Android has the same issue for both critical and non-critical updates (see synonymdev/bitkit-android)