ensured timetable visibility on widget navigation by resetting root navigator

lib/app.dart

@@ -65,6 +65,14 @@ class _AppState extends State<App> with WidgetsBindingObserver {
   Future<void> _handlePendingWidgetNavigation() async {
     final pending = await WidgetNavigation.consumePendingTimetableTap();
     if (!pending || !mounted) return;
+    // Routes pushed with `withNavBar: false` (chat views, file viewers, …)
+    // sit on the root navigator above the bottom-nav, so a bare jumpToTab
+    // would swap the tab behind them and leave the user staring at the
+    // previous screen. Reset to the tab root first.
+    final navigator = Navigator.of(context);
+    if (navigator.canPop()) {
+      navigator.popUntil((route) => route.isFirst);
+    }
     AppRoutes.goToTab(context, Modules.timetable);
   }