fix(detail): render both phases for all-through schools (Batch E)

Batch E of applying the compare-screen learnings to the school detail page —
all-through handling (point 11).

An all-through school carries both KS2 and KS4 figures in the same yearly
rows, but SchoolDetailView flipped it to isSecondary and rendered GCSE-only,
hiding the entire primary phase (SATs, phonics, KS2 trend). The Results
snapshot already gated its KS2/KS4 blocks purely on data availability, so both
already appeared there — but the section title, the trend chart, phonics, the
nav label and the history table all still assumed a single phase.

- Add an explicit `isAllThrough` flag (+ `showPrimaryContent = isPrimary ||
  isAllThrough`); pure-secondary behaviour is unchanged.
- Hero: an "All-through (primary & secondary)" meta chip for all-ages framing.
- Results section: title "SATs & GCSE Results", a combined subtitle, and
  "Primary — KS2 SATs (Year 6)" / "Secondary — GCSEs (Year 11)" sub-headings
  separating the two blocks.
- Results Over Time: render two stacked PerformanceCharts (KS2 SATs + GCSEs)
  rather than crowding both stages' series — on different scales with
  different gap stories — onto one axis. Each gets its correct England overlay.
- Phonics section + nav item now show for all-through (primary-stage metric).
- History table: an all-through column set covering both phases (RWM, Exceeding,
  Attainment 8, Progress 8, Eng & Maths 4+).
- Nav "Results" label for all-through instead of "GCSEs".

e2e: a new journey asserts an all-through school (Hessle, 137306) shows both
the KS2 and KS4 results and the All-through label, with a data-driven
precondition skip if staging data drifts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0146VHeLAWjDVE2B5uU67jCB

e2e/tests/journeys.spec.ts

@@ -148,6 +148,37 @@ test('a report-card school shows its report card, dated to the report-card inspe
   }
 });
 
+test('an all-through school shows BOTH its KS2 SATs and its GCSE results, not just one phase', async ({ page }) => {
+  // All-through schools carry both KS2 and KS4 data in the same yearly rows.
+  // The detail view used to flip them to isSecondary and render GCSE-only,
+  // hiding the primary phase. It now renders both phases and labels the school
+  // "All-through".
+  const AT_URN = 137306; // Hessle High School and Penshurst Primary — all-through
+  const res = await page.request.get(`/api/schools/${AT_URN}`);
+  expect(res.ok()).toBeTruthy();
+  const detail = await res.json();
+  const rows: Array<{ rwm_expected_pct: number | null; attainment_8_score: number | null }> =
+    detail.yearly_data ?? [];
+  const hasKS2 = rows.some((r) => r.rwm_expected_pct != null);
+  const hasKS4 = rows.some((r) => r.attainment_8_score != null);
+  test.skip(
+    (detail.school_info?.phase ?? '').toLowerCase() !== 'all-through' || !hasKS2 || !hasKS4,
+    'precondition: chosen URN must currently be all-through with both KS2 and KS4 results',
+  );
+
+  await page.goto(`/school/${AT_URN}`);
+  await expect(page.locator('h1').first()).toBeVisible({ timeout: 15_000 });
+
+  // Labelled as all-through in the hero meta.
+  await expect(page.getByText(/All-through/i).first()).toBeVisible();
+
+  // The combined results section carries both phases.
+  const results = page.locator('#results');
+  await expect(results.getByText(/SATs & GCSE Results/)).toBeVisible();
+  await expect(results.getByText('Reading, Writing & Maths combined')).toBeVisible(); // KS2
+  await expect(results.getByText('Attainment 8').first()).toBeVisible(); // KS4
+});
+
 test('school with no performance data still gets a working detail page', async ({ page }) => {
   // Schools without KS2/KS4 results (special post-16 institutions, sixth-form
   // centres, PRUs) used to 500 in the API — NaN GIAS fields broke JSON