feat(mobile): section-nav scroll affordance and drop illegible home previews

MOB-03: The school-detail section nav (SATs / Admissions / Pupils /
Location / History) overflows on phones (scrollWidth 462 vs clientWidth
356) with no signal that more tabs exist past the right edge. Add a
right-edge mask-image fade at ≤640px, scroll-snap on each link, and
bigger tap targets (min-height 36px, padding bumped). A scroll/resize
listener toggles an .atEnd class that removes the fade once the user
has scrolled to the last tab.

MOB-04: The "What you'll see on every school" cards rendered preview
visuals (mini cascade chart, Ofsted badge, compare table) with text
scaled down to 6–10px — unreadable on a phone. Hide .hiwVisual at
≤640px and let the explanatory text carry each card; tiny visible
text count on the home dropped from 51 to 8.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

nextjs-app/components/HomeView.module.css

@@ -1003,6 +1003,24 @@
   }
 }
 
+/* On phones, hide the scaled-down preview visuals (text becomes illegible
+   at this size) and let the explanatory text carry each card. */
+@media (max-width: 640px) {
+  .hiwVisual {
+    display: none;
+  }
+  .hiwCard {
+    padding: 1rem 1.1rem;
+    gap: 0.45rem;
+  }
+  .hiwTitle {
+    font-size: 1.05rem;
+  }
+  .hiwDesc {
+    font-size: 0.9rem;
+  }
+}
+
 /* ── Editorial section ───────────────────────────────── */
 
 .editorial {