perf(map): reuse resources across routes

Preserve standard network layers between map pages while disposing route-owned overlays and controls to prevent memory growth.

src/app/(main)/(map)/scada-data-cleaning/loading.tsx

@@ -0,0 +1,5 @@
+import { MapSkeleton } from "@components/loading/MapSkeleton";
+
+export default function Loading() {
+  return <MapSkeleton />;
+}