feat(mobile): mobile cleanups for deadlines, result cards, tooltips, ofsted, rankings

MOB-07: Admissions deadlines strip becomes a horizontal snap-scroller
on ≤640px instead of a cramped 2×2 grid (which forced "Secondary ·
Deadline" track labels down to 9.6px). Cards stay readable, the right
edge fades to signal more content past the viewport, .chipTrack font
bumped to 0.7rem.

MOB-09: Result-card line3 (headline metric + secondary stats) was
crowding everything onto one row. Force the first .stat (Attainment
8 / RWM headline) to flex-basis 100% on mobile so delta-vs-LA and
pupil count wrap below it with a visible row-gap. Applied to both
SchoolRow (primary) and SecondarySchoolRow.

MOB-12: MetricTooltip ⓘ icons rendered at ~9px and relied on :hover
(which doesn't fire on touch). Hide the whole .wrapper at ≤640px —
metric labels themselves carry the meaning. Saves building a
tap-to-show layer for now.

MOB-13: The "Ofsted pending / No inspection on record" empty state
took a full hero card to communicate non-information. Add a
data-ofsted-state attribute on the hero chip; on ≤640px, the
"none" state collapses to a single muted line.

MOB-17: Already had Type+Action columns hidden on rankings mobile —
no change needed beyond marking complete.

MOB-18: Long metric headers ("Reading, Writing & Maths Combined %")
forced the value column wide. Drop .valueHeader to 0.625rem with
white-space: normal at ≤640px so labels wrap onto 2 short lines.

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

nextjs-app/components/MetricTooltip.module.css

@@ -81,3 +81,13 @@
     width: 180px;
   }
 }
+
+/* On phones the icon was rendering at ~9px and the tooltip relied on
+   :hover, which doesn't fire on touch. Rather than build a tap-to-show
+   layer with backdrop dismissal, hide the helper entirely — the metric
+   labels themselves carry the meaning. */
+@media (max-width: 640px) {
+  .wrapper {
+    display: none;
+  }
+}