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/unread_divider.dart

@@ -1,30 +1,49 @@
 import 'package:flutter/material.dart';
 
 import '../l10n/l10n.dart';
+import '../theme/mesh_theme.dart';
 
 class UnreadDivider extends StatelessWidget {
   const UnreadDivider({super.key});
 
   @override
   Widget build(BuildContext context) {
-    final color = Theme.of(context).colorScheme.primary;
+    final scheme = Theme.of(context).colorScheme;
+    final color = scheme.primary;
     return Padding(
-      padding: const EdgeInsets.symmetric(vertical: 8),
+      padding: const EdgeInsets.symmetric(vertical: 10),
       child: Row(
         children: [
-          Expanded(child: Divider(color: color)),
-          Padding(
-            padding: const EdgeInsets.symmetric(horizontal: 8),
+          Expanded(
+            child: Container(
+              height: 1,
+              color: color.withValues(alpha: 0.25),
+            ),
+          ),
+          const SizedBox(width: 10),
+          Container(
+            padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 4),
+            decoration: BoxDecoration(
+              color: color.withValues(alpha: 0.12),
+              borderRadius: BorderRadius.circular(MeshRadii.pill),
+              border: Border.all(color: color.withValues(alpha: 0.35)),
+            ),
             child: Text(
               context.l10n.chat_newMessages,
-              style: TextStyle(
+              style: MeshTheme.mono(
+                fontSize: 10.5,
+                fontWeight: FontWeight.w600,
                 color: color,
-                fontSize: 12,
-                fontWeight: FontWeight.w500,
               ),
             ),
           ),
-          Expanded(child: Divider(color: color)),
+          const SizedBox(width: 10),
+          Expanded(
+            child: Container(
+              height: 1,
+              color: color.withValues(alpha: 0.25),
+            ),
+          ),
         ],
       ),
     );