Show Non-Dismissible Alert if `currentActivity` is `null` on App Start

[Parveshdhull]

Description

If currentActivity is null when the app starts, it leads to an unusable state where users can't access accounts or create new ones. To prevent users from being stuck in this state, we should display a native, non-dismissible alert. The alert should inform the user that the app started in an unusual state and prompt them to force close and restart the app. more details: https://github.com/status-im/status-mobile/issues/20930#issuecomment-2454491957 https://github.com/status-im/status-mobile/pull/21553#issuecomment-2456518549

Expected Behavior:

• Show a non-dismissible native alert if currentActivity is null during app startup.
• The alert should instruct the user to force close and restart the app.