feat(secondary): apply primary visual design to secondary school detail

- GCSE top metrics (Att8, P8, Eng+Maths 4+/5+) promoted to heroStatCard
  teal-tinted cards with Playfair serif values and DeltaChip vs national
- Attainment 8 visual bar: 0–80 scale with coral national-average marker
  and pill label, mirrors the SatsChart concept for a score metric
- Progress 8 number line: −3 to +3 axis showing CI band, zero baseline,
  and a teal/coral dot for the school's score (hidden when P8 suspended)
- SEN section upgraded from plain metricCard to heroStatCard grid
- History table moved into a details/summary accordion (collapsed by
  default); PerformanceChart now lives at the top of the History section
  always visible above the disclosure

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

nextjs-app/components/SecondarySchoolDetailView.module.css

@@ -802,6 +802,207 @@
   color: var(--text-muted, #8a847a);
 }
 
+/* ── GCSE hero stat cards (mirrors primary heroStatCard) ─ */
+.heroStatGrid {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
+  gap: 0.85rem;
+  margin-bottom: 0.25rem;
+}
+
+.heroStatCard {
+  background: rgba(45, 125, 125, 0.1);
+  border: 1px solid rgba(45, 125, 125, 0.2);
+  border-radius: 12px;
+  padding: 1rem 1.1rem;
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+}
+
+.heroStatCard .heroStatLabel {
+  font-size: 0.6rem;
+  font-weight: 700;
+  text-transform: uppercase;
+  letter-spacing: 0.08em;
+  color: var(--text-muted, #6d685f);
+}
+
+.heroStatCard .heroStatValue {
+  font-family: var(--font-playfair), 'Playfair Display', serif;
+  font-size: 2.1rem;
+  font-weight: 700;
+  line-height: 1;
+  color: var(--accent-teal, #2d7d7d);
+  display: flex;
+  align-items: baseline;
+  gap: 0.4rem;
+  flex-wrap: wrap;
+}
+
+.heroStatCard .heroStatHint {
+  font-size: 0.7rem;
+  color: var(--text-muted, #6d685f);
+  font-style: normal;
+  margin-top: 0;
+}
+
+/* ── Attainment 8 visual bar ─────────────────────────── */
+.att8Viz {
+  margin: 1.25rem 0 0.5rem;
+}
+
+.att8VizLabel {
+  font-size: 0.6875rem;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.07em;
+  color: var(--text-muted, #6d685f);
+  margin-bottom: 0.5rem;
+}
+
+.att8VizTrack {
+  position: relative;
+  height: 14px;
+  background: rgba(45, 125, 125, 0.08);
+  border: 1px solid var(--border-color, #e5dfd5);
+  border-radius: 4px;
+  overflow: visible;
+}
+
+.att8VizFill {
+  height: 100%;
+  background: var(--accent-teal, #2d7d7d);
+  border-radius: 4px 0 0 4px;
+  transition: width 0.6s ease;
+}
+
+.att8VizNatLine {
+  position: absolute;
+  top: -4px;
+  bottom: -4px;
+  width: 2px;
+  background: var(--accent-coral, #e07256);
+  border-radius: 2px;
+  z-index: 2;
+}
+
+.att8VizNatPill {
+  position: absolute;
+  top: -20px;
+  transform: translateX(-50%);
+  background: var(--accent-coral, #e07256);
+  color: #fff;
+  font-size: 0.6rem;
+  font-weight: 700;
+  padding: 0.1rem 0.3rem;
+  border-radius: 3px;
+  white-space: nowrap;
+}
+
+.att8VizTicks {
+  display: flex;
+  justify-content: space-between;
+  margin-top: 0.25rem;
+  font-size: 0.6rem;
+  color: var(--text-muted, #6d685f);
+}
+
+/* ── Progress 8 number line ──────────────────────────── */
+.p8Viz {
+  margin: 1.25rem 0 0.5rem;
+}
+
+.p8VizLabel {
+  font-size: 0.6875rem;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.07em;
+  color: var(--text-muted, #6d685f);
+  margin-bottom: 0.5rem;
+}
+
+.p8VizTrack {
+  position: relative;
+  height: 14px;
+  background: rgba(45, 125, 125, 0.06);
+  border: 1px solid var(--border-color, #e5dfd5);
+  border-radius: 4px;
+  overflow: visible;
+}
+
+.p8VizCi {
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  background: rgba(45, 125, 125, 0.18);
+  border-radius: 3px;
+}
+
+.p8VizZero {
+  position: absolute;
+  top: -4px;
+  bottom: -4px;
+  width: 2px;
+  background: var(--border-color, #e5dfd5);
+  z-index: 1;
+}
+
+.p8VizDot {
+  position: absolute;
+  top: 50%;
+  transform: translate(-50%, -50%);
+  width: 12px;
+  height: 12px;
+  border-radius: 50%;
+  background: var(--accent-teal, #2d7d7d);
+  border: 2px solid white;
+  box-shadow: 0 1px 4px rgba(0,0,0,0.2);
+  z-index: 3;
+}
+
+.p8VizDotNeg {
+  background: var(--accent-coral, #e07256);
+}
+
+.p8VizTicks {
+  display: flex;
+  justify-content: space-between;
+  margin-top: 0.25rem;
+  font-size: 0.6rem;
+  color: var(--text-muted, #6d685f);
+}
+
+/* ── History accordion ───────────────────────────────── */
+.historyDisclosure {
+  margin-top: 1rem;
+}
+
+.historyToggle {
+  list-style: none;
+  cursor: pointer;
+  font-size: 0.8125rem;
+  font-weight: 600;
+  color: var(--text-muted, #6d685f);
+  padding: 0.5rem 0;
+  display: flex;
+  align-items: center;
+  gap: 0.375rem;
+  user-select: none;
+}
+
+.historyToggle::-webkit-details-marker { display: none; }
+
+.historyToggle::before {
+  content: '▶';
+  font-size: 0.6rem;
+  transition: transform 0.2s ease;
+}
+
+.historyDisclosure[open] .historyToggle::before {
+  transform: rotate(90deg);
+}
+
 /* ── Responsive ──────────────────────────────────────── */
 @media (max-width: 768px) {
   .header {
@@ -848,6 +1049,14 @@
     font-size: 1rem;
   }
 
+  .heroStatGrid {
+    grid-template-columns: 1fr;
+  }
+
+  .heroStatCard .heroStatValue {
+    font-size: 1.85rem;
+  }
+
   .chartContainer {
     height: 220px;
   }