autoHideOnModal property

When true (default), destroys the native container's PlatformView while a modal sheet is presented above this widget's host route. Prevents the iOS hybrid-composition z-order bleed (Issue #53) where host-page PlatformView pixels leak through a sheet that also contains a CN-widget. Requires CNTabBarRouteObserver() to be registered in the app's navigatorObservers. No effect on iOS < 26 / non-iOS (fallback path returns the child unchanged).