fix: add isolate on main and z-0 on map container to fix z-index stacking with Header

frontend/src/app/page.tsx

@@ -6,7 +6,7 @@ const MapView = dynamic(() => import('@/components/MapView'), { ssr: false })
 
 export default function HomePage() {
   return (
-    <main className="relative h-screen w-screen overflow-hidden">
+    <main className="relative isolate h-screen w-screen overflow-hidden">
       <MapView />
     </main>
   )

frontend/src/components/MapView.tsx

@@ -116,7 +116,7 @@ export default function MapView() {
           </div>
         </div>
       ) : (
-        <div ref={containerRef} className="h-full w-full" />
+        <div ref={containerRef} className="z-0 h-full w-full" />
       )}
 
       {!user && !isLoading && !mapError && (