fix(school): make hero map fullscreen work on iOS Safari

iOS Safari has no Element.requestFullscreen (fullscreen is video-only),
so tapping the map band or 'View on map' silently did nothing on
iPhones. Fall back to a fixed-position CSS overlay driven by state when
the Fullscreen API is missing or its promise rejects, locking body
scroll while open. The Leaflet map already re-measures via the shared
isFullscreen flag. New e2e journey simulates the iOS condition by
deleting the API and asserts the overlay opens and closes; it fails
against the current production build.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

nextjs-app/components/SchoolHeroMap.module.css

@@ -34,6 +34,15 @@
     background: #fff;
 }
 
+/* Fallback fullscreen (iOS Safari — no Element.requestFullscreen): the API
+   can't promote the element, so pin it over the page ourselves. Above the
+   comparison toast (3000) and everything else except modals (9999+). */
+.wrapper[data-fs-fallback] {
+    position: fixed;
+    inset: 0;
+    z-index: 5000;
+}
+
 .skeleton {
     width: 100%;
     height: 100%;