refactor(detail): render sections on the server behind a client shell

page.tsx now composes the sections and passes them through SchoolDetailShell
as children, so ~1,300 lines of static markup stop shipping as client
JavaScript. The shell keeps what is genuinely interactive: back link, header
reveal, hero map, compare CTA, sticky nav and scroll-spy.

The scroll-spy already located sections via document.getElementById, so it
works unchanged against server-rendered children.

Charts needed a client wrapper: next/dynamic with ssr:false is illegal in a
Server Component, so components/school/charts.tsx is the boundary that keeps
Chart.js (64 KB gz) lazy and browser-only.

Measured on this build:
- school route client chunk: 8 KB gz (33 KB raw)
- total static JS across all chunks: 380.6 -> 350.7 KB gz
- section markup is absent from every client chunk ("Got their first choice",
  "Ofsted reports", "Most deprived" etc. all return 0 hits); shell strings
  still present, as expected
- shared baseline unchanged at 172 KB gz -- out of scope, as designed

The 14 characterization tests pass byte-identical to the commit that
introduced them. Only the render helper changed.

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

nextjs-app/components/school/PrimarySchoolSections.tsx

@@ -0,0 +1,139 @@
+/**
+ * PrimarySchoolSections — the section sequence for primary and all-through
+ * detail pages. Server component.
+ *
+ * All-through schools route here rather than to SecondarySchoolSections,
+ * because this list renders BOTH the KS2 and KS4 blocks (ResultsSection and
+ * HistorySection branch on isAllThrough); the secondary list is KS4-only and
+ * would silently drop their SATs data.
+ *
+ * The render conditions here MUST match buildNavItems in lib/schoolSections,
+ * or the sticky nav will link to sections that do not exist.
+ */
+
+import type {
+  School, SchoolResult, AbsenceData, OfstedInspection, SchoolCensus,
+  SchoolAdmissions, SchoolDeprivation, SchoolFinance, NationalAverages,
+} from '@/lib/types';
+import { ofstedLegacyAreas } from '@/lib/utils';
+import type { SchoolFlags } from '@/lib/schoolSections';
+import { OfstedSection } from './OfstedSection';
+import { ResultsSection } from './ResultsSection';
+import { AdmissionsSection } from './AdmissionsSection';
+import { InclusionSection } from './InclusionSection';
+import { HistorySection } from './HistorySection';
+import { SchoolLifeSection } from './SchoolLifeSection';
+import { LocalAreaSection } from './LocalAreaSection';
+import { FinancesSection } from './FinancesSection';
+
+export interface PrimarySchoolSectionsProps {
+  schoolInfo: School;
+  yearlyData: SchoolResult[];
+  absenceData: AbsenceData | null;
+  ofsted: OfstedInspection | null;
+  census: SchoolCensus | null;
+  admissions: SchoolAdmissions | null;
+  admissionsHistory: SchoolAdmissions[];
+  deprivation: SchoolDeprivation | null;
+  finance: SchoolFinance | null;
+  nationalAvg: NationalAverages | null;
+  flags: SchoolFlags;
+}
+
+export function PrimarySchoolSections({
+  schoolInfo, yearlyData, absenceData, ofsted, census,
+  admissions, admissionsHistory, deprivation, finance, nationalAvg, flags,
+}: PrimarySchoolSectionsProps) {
+  const primaryAvg = nationalAvg?.primary ?? {};
+  const secondaryAvg = nationalAvg?.secondary ?? {};
+
+  const isReportCard = !!(ofsted?.report_card && Object.keys(ofsted.report_card).length > 0);
+  // Report cards are dated by their own inspection (rc_inspection_date), never
+  // the legacy inspection_date (report cards exist only from Nov 2025).
+  const ofstedInspectedDate = isReportCard
+    ? ofsted?.rc_inspection_date ?? null
+    : ofsted?.inspection_date ?? null;
+  const oeifAreas = ofsted ? ofstedLegacyAreas(ofsted) : [];
+  const oeifAllSameGrade =
+    !!ofsted &&
+    !isReportCard &&
+    oeifAreas.length >= 3 &&
+    oeifAreas.every((a) => a.value === ofsted.overall_effectiveness);
+
+  return (
+    <>
+      {ofsted && (
+        <OfstedSection
+          ofsted={ofsted}
+          urn={schoolInfo.urn}
+          isReportCard={isReportCard}
+          ofstedInspectedDate={ofstedInspectedDate}
+          oeifAllSameGrade={oeifAllSameGrade}
+          oeifAreas={oeifAreas}
+          variant="primary"
+        />
+      )}
+
+      {flags.hasAnyResults && flags.latestResults && (
+        <ResultsSection
+          latestResults={flags.latestResults}
+          schoolInfo={schoolInfo}
+          primaryAvg={primaryAvg}
+          secondaryAvg={secondaryAvg}
+          isAllThrough={flags.isAllThrough}
+          isSecondary={flags.isSecondary}
+          isSpecial={flags.isSpecial}
+          hasKS2Results={flags.hasKS2Results}
+          hasKS4Results={flags.hasKS4Results}
+          ks2Placeholder={flags.ks2Placeholder}
+          suppressKs2Comparison={flags.suppressKs2Comparison}
+          suppressKs4Comparison={flags.suppressKs4Comparison}
+        />
+      )}
+
+      {admissions && (
+        <AdmissionsSection
+          admissions={admissions}
+          admissionsHistory={admissionsHistory}
+          isAllThrough={flags.isAllThrough}
+        />
+      )}
+
+      {flags.hasInclusionData && (
+        <InclusionSection
+          latestResults={flags.latestResults}
+          census={census}
+          hasGenderSplit={flags.hasGenderSplit}
+          primaryAvg={primaryAvg}
+        />
+      )}
+
+      {yearlyData.length > 0 && (
+        <HistorySection
+          yearlyData={yearlyData}
+          schoolInfo={schoolInfo}
+          nationalAvg={nationalAvg}
+          primaryAvg={primaryAvg}
+          secondaryAvg={secondaryAvg}
+          isAllThrough={flags.isAllThrough}
+          isPrimary={flags.isPrimary}
+          isSecondary={flags.isSecondary}
+          hasKS2Results={flags.hasKS2Results}
+          hasKS4Results={flags.hasKS4Results}
+          suppressKs2Comparison={flags.suppressKs2Comparison}
+          suppressKs4Comparison={flags.suppressKs4Comparison}
+        />
+      )}
+
+      {flags.hasSchoolLife && (
+        <SchoolLifeSection absenceData={absenceData} primaryAvg={primaryAvg} />
+      )}
+
+      {flags.hasDeprivation && deprivation && (
+        <LocalAreaSection deprivation={deprivation} />
+      )}
+
+      {flags.hasFinance && finance && <FinancesSection finance={finance} />}
+    </>
+  );
+}