Introduce a "Test Notification" preference in the settings menu to allow users to verify the notification system. This preference is automatically hidden on Android TV devices to maintain a clean UI.
Additionally, refactor notification permission handling to skip requests on Android TV and improve the internal check for Leanback support using a lazy property.
Updated string resources for the new preference across all supported languages.
Add the `notification_channel_description` string resource to the
default and all localized string files to provide context for the
notification channel.
Add NotificationSys to manage system notifications and update
MainActivity to request POST_NOTIFICATIONS permission on Android 13+.
Includes localized string resources for notification testing and
permission error feedback.
Add a new security preference in the settings screen that links to the
SECURITY.md file on GitHub. This includes a new security icon and
localized strings for multiple languages.