fix: improve DialogShell scroll, PageHeader layout, add HideBottomNav widget

lib/magic_starter.dart

@@ -45,4 +45,5 @@ export 'src/ui/widgets/magic_starter_two_factor_modal.dart';
 export 'src/ui/widgets/magic_starter_timezone_select.dart';
 export 'src/ui/widgets/magic_starter_page_header.dart';
 export 'src/ui/widgets/magic_starter_dialog_shell.dart';
+export 'src/ui/widgets/magic_starter_hide_bottom_nav.dart';
 export 'src/ui/views/teams/magic_starter_team_invitation_accept_view.dart';

lib/src/ui/layouts/magic_starter_app_layout.dart

@@ -8,6 +8,7 @@ import '../../magic_starter_manager.dart';
 import '../widgets/magic_starter_team_selector.dart';
 import '../widgets/magic_starter_user_profile_dropdown.dart';
 import 'package:magic_notifications/magic_notifications.dart';
+import '../widgets/magic_starter_hide_bottom_nav.dart';
 import '../widgets/magic_starter_notification_dropdown.dart';
 
 /// Default App Layout for Magic Starter.
@@ -132,7 +133,9 @@ class _MagicStarterAppLayoutState extends State<MagicStarterAppLayout> {
               ],
             ),
           ),
-          bottomNavigationBar: (!isDesktop && hasBottomNav)
+          bottomNavigationBar: (!isDesktop &&
+                  hasBottomNav &&
+                  !MagicStarterHideBottomNav.of(context))
               ? _buildBottomNav(context, currentPath)
               : null,
         );

lib/src/ui/widgets/magic_starter_hide_bottom_nav.dart

@@ -0,0 +1,41 @@
+import 'package:flutter/widgets.dart';
+
+/// Signals to `MagicStarterAppLayout` that the bottom navigation bar
+/// should be hidden for routes nested under this widget.
+///
+/// Wrap a layout with this widget to suppress the mobile bottom navigation
+/// bar for specific route groups (e.g., fullscreen views, media players,
+/// chat screens).
+///
+/// ## Usage
+///
+/// ```dart
+/// MagicRoute.group(
+///   layout: (child) => MagicStarterHideBottomNav(
+///     child: MagicStarter.view.makeLayout('layout.app', child: child),
+///   ),
+///   layoutId: 'app.fullscreen',
+///   routes: () { ... },
+/// );
+/// ```
+///
+/// In your layout's `build` method, check whether to show bottom nav:
+///
+/// ```dart
+/// if (!MagicStarterHideBottomNav.of(context)) _buildBottomNav(),
+/// ```
+class MagicStarterHideBottomNav extends InheritedWidget {
+  /// Creates a [MagicStarterHideBottomNav] that hides bottom navigation
+  /// for its subtree.
+  const MagicStarterHideBottomNav({super.key, required super.child});
+
+  /// Returns `true` if a [MagicStarterHideBottomNav] exists above [context].
+  static bool of(BuildContext context) {
+    return context
+            .dependOnInheritedWidgetOfExactType<MagicStarterHideBottomNav>() !=
+        null;
+  }
+
+  @override
+  bool updateShouldNotify(MagicStarterHideBottomNav oldWidget) => false;
+}