fix(rankings,admissions): correct accuracy issues from education audit

Follow-up audit of the rankings and admissions pages.

Admissions (AdmissionsView.tsx):
- National Offer Day no longer claims offers publish "from 12:01 am";
  release times are set per-council (often late afternoon, some
  overnight), so it now tells parents to check their council's page.
- Secondary preference count no longer states a flat "up to six"
  (that's London/Pan-London); most LAs allow three to six. Mirrors the
  hedge the primary step already used.
- Added the two deadlines that most often catch parents out: selective
  schools' separate entrance-test registration (months earlier), and
  faith schools' supplementary information form sent direct to the
  school. Covered in both the primary and secondary criteria steps.
- Reworded the equal-preference tip so it's precise: order is the
  tie-break among schools you qualify for (you get the highest-ranked
  one), not irrelevant.

Rankings (RankingsView.tsx):
- Subtitle "Top-performing schools by X" -> "Schools ranked by X", so
  it isn't nonsensical for context/equity/absence metrics.
- KS2 progress isn't published for 2023/24 or 2024/25 (no KS1
  baseline). Selecting a primary progress metric on a recent year used
  to dead-end on a generic "No rankings found". Added a scoped caveat
  to the progress hint and an explanatory empty-state (primary only —
  secondary Progress 8 is published).

Added an admissions smoke journey (static content, stable milestones).
Verified with tsc --noEmit and next build.

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

e2e/tests/journeys.spec.ts

@@ -438,6 +438,18 @@ test('compare chart on mobile shows school chips with tap-to-focus', async ({ pa
   await expect(chips.first()).toHaveAttribute('aria-pressed', 'false');
 });
 
+test('admissions guide renders its key milestones', async ({ page }) => {
+  // Static content page — assert the guide loads and the load-bearing
+  // milestones parents rely on are present (dates are statutory, so these
+  // strings are stable invariants, not data-refresh-sensitive).
+  await page.goto('/admissions');
+  await expect(page.getByRole('heading', { name: /School Admissions Guide/i })).toBeVisible();
+  await expect(page.getByRole('heading', { name: /Primary school admissions/i })).toBeVisible();
+  await expect(page.getByRole('heading', { name: /Secondary school admissions/i })).toBeVisible();
+  // National Offer Day is the milestone the whole guide builds toward.
+  await expect(page.getByText(/National Offer Day/i).first()).toBeVisible();
+});
+
 test('rankings page loads a populated table', async ({ page }) => {
   await page.goto('/rankings');
   await expect(page.getByRole('heading', { name: /rankings/i }).first()).toBeVisible();