Add "Search in bottom bar" to Settings

New Settings > Appearance toggle moves Search into the bottom bar and
out of the top bar, so there's only one search entry point on screen.
Tapping it pushes SearchView same as before - it's never highlighted,
since it isn't a real destination.

- Attached: Search becomes the row's last item, styled like any other
  tab but permanently idle.
- Floating: Search gets its own separate, always fully round satellite
  circle beside the bar instead.

Enabling it costs one regular tab: SettingsController.maxVisibleTabs
is now a dynamic getter (defaultMaxVisibleTabs - 1 while the toggle is
on) instead of the old flat constant, re-enforced immediately if the
user already has all 5 slots filled - the same cleanup path used for
a fresh install or an app update that added a new tab.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

lib/widgets/bottom_nav_bar.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
 import '../models/app_tab.dart';
 import 'noo/nav/noo_bottom_bar.dart';
 
@@ -7,12 +8,18 @@ import 'noo/nav/noo_bottom_bar.dart';
 /// doesn't need to import `noo/nav` itself. [selectedIndex] may be -1 (no
 /// destination highlighted) when the shell is showing a tab opened from the
 /// drawer's "More" list that isn't one of the pinned [tabs].
+///
+/// [onSearchTap] (from Settings' "Search in bottom bar") adds the Search
+/// entry [NooBottomBar] itself knows how to place (row's last item when
+/// attached, its own satellite when floating) - null leaves the bar
+/// exactly as before.
 class BottomNavBar extends StatelessWidget {
   final NooNavStyle style;
   final NooBottomBarStyle barStyle;
   final List<AppTab> tabs;
   final int selectedIndex;
   final ValueChanged<int> onDestinationSelected;
+  final VoidCallback? onSearchTap;
 
   const BottomNavBar({
     super.key,
@@ -21,6 +28,7 @@ class BottomNavBar extends StatelessWidget {
     required this.tabs,
     required this.selectedIndex,
     required this.onDestinationSelected,
+    this.onSearchTap,
   });
 
   @override
@@ -34,6 +42,10 @@ class BottomNavBar extends StatelessWidget {
       ],
       selectedIndex: selectedIndex,
       onSelected: onDestinationSelected,
+      searchDestination: onSearchTap == null
+          ? null
+          : const NooNavDestination(icon: LucideIcons.search, label: 'Search'),
+      onSearchTap: onSearchTap,
     );
   }
 }