Implement error handling and visual enhancements in map components

- Introduced MapErrorBoundary component to handle map loading errors gracefully.
- Enhanced MapView with a reconnection status indicator for live updates.
- Added tile freshness animation to indicate updated tiles visually.
- Preloaded marker icon images to improve rendering performance.
- Updated various pages to utilize the new MapErrorBoundary for better user experience.

frontend-nuxt/assets/css/leaflet-overrides.css

@@ -8,3 +8,18 @@
 .leaflet-tile {
   visibility: visible !important;
 }
+
+/* Brief highlight when a tile is updated via SSE (tile freshness indicator). */
+@keyframes tile-fresh-glow {
+  0% {
+    filter: brightness(1.15);
+    box-shadow: 0 0 0 0 oklch(0.6 0.2 264 / 0.4);
+  }
+  100% {
+    filter: brightness(1);
+    box-shadow: none;
+  }
+}
+.leaflet-tile.tile-fresh {
+  animation: tile-fresh-glow 0.6s ease-out;
+}