Add shared UI components for mesh application

- Introduced `mesh_ui.dart` with reusable widgets including SectionHeader, MeshCard, StatusChip, StatTile, AvatarCircle, SignalBars, RouteChip, PulseDot, BottomSheetHeader, ErrorRetryCard, and ListEntrance.
- Implemented `path_map_ui.dart` for path map screens, featuring path distance calculations, playback controls, and a summary list of observed paths.
- Created `themed_map_tile_layer.dart` for shared cached map tiles with automatic dark-mode treatment.

lib/widgets/quick_switch_bar.dart

@@ -2,12 +2,14 @@ import 'dart:ui';
 
 import 'package:flutter/material.dart';
 import '../l10n/l10n.dart';
+import '../theme/mesh_theme.dart';
 
 class QuickSwitchBar extends StatelessWidget {
   final int selectedIndex;
   final ValueChanged<int> onDestinationSelected;
   final int contactsUnreadCount;
   final int channelsUnreadCount;
+  final bool highContrast;
 
   const QuickSwitchBar({
     super.key,
@@ -15,6 +17,7 @@ class QuickSwitchBar extends StatelessWidget {
     required this.onDestinationSelected,
     this.contactsUnreadCount = 0,
     this.channelsUnreadCount = 0,
+    this.highContrast = false,
   });
 
   @override
@@ -22,6 +25,14 @@ class QuickSwitchBar extends StatelessWidget {
     final theme = Theme.of(context);
     final colorScheme = theme.colorScheme;
     final labelStyle = theme.textTheme.labelMedium ?? const TextStyle();
+    final background = highContrast ? MapPalette.panelDark : Colors.transparent;
+    final selectedColor = highContrast
+        ? MapPalette.textPrimary
+        : colorScheme.onPrimary;
+    final unselectedColor = highContrast
+        ? MapPalette.textSecondary
+        : colorScheme.onSurfaceVariant;
+    final indicator = highContrast ? MapPalette.selected : colorScheme.primary;
 
     return SizedBox(
       width: double.infinity,
@@ -31,9 +42,11 @@ class QuickSwitchBar extends StatelessWidget {
           filter: ImageFilter.blur(sigmaX: 14, sigmaY: 14),
           child: DecoratedBox(
             decoration: BoxDecoration(
-              color: Colors.transparent,
+              color: background,
               border: Border.all(
-                color: colorScheme.outlineVariant.withValues(alpha: 0.4),
+                color: highContrast
+                    ? MapPalette.border
+                    : colorScheme.outlineVariant.withValues(alpha: 0.4),
               ),
             ),
             child: NavigationBarTheme(
@@ -41,22 +54,18 @@ class QuickSwitchBar extends StatelessWidget {
                 backgroundColor: Colors.transparent,
                 surfaceTintColor: Colors.transparent,
                 shadowColor: Colors.transparent,
-                indicatorColor: colorScheme.primaryContainer,
+                indicatorColor: indicator,
                 labelTextStyle: WidgetStateProperty.resolveWith((states) {
                   final isSelected = states.contains(WidgetState.selected);
                   return labelStyle.copyWith(
                     fontWeight: isSelected ? FontWeight.w700 : FontWeight.w500,
-                    color: isSelected
-                        ? colorScheme.onPrimaryContainer
-                        : colorScheme.onSurfaceVariant,
+                    color: isSelected ? selectedColor : unselectedColor,
                   );
                 }),
                 iconTheme: WidgetStateProperty.resolveWith((states) {
                   final isSelected = states.contains(WidgetState.selected);
                   return IconThemeData(
-                    color: isSelected
-                        ? colorScheme.onPrimaryContainer
-                        : colorScheme.onSurfaceVariant,
+                    color: isSelected ? selectedColor : unselectedColor,
                   );
                 }),
               ),