feat(destinations): the After Year 11 section

Question cards over one bar, with the cards acting as a lens on the bar
rather than a summary beside it — focusing a card dims everything it is
not made of, so the grouping we chose is inspectable rather than asserted.

The bar renders only when canRenderBar allows it. Where a category is
withheld the section says so and shows the table instead: the categories
sum to the cohort, so a bar drawn from the published segments leaves a
gap whose width is the withheld figure.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BvdDKvFFSZuMVDH5fEyTob

nextjs-app/lib/types.ts

@@ -369,6 +369,12 @@ export interface SchoolDetailsResponse {
   admission_distance?: SchoolAdmissionDistance | null;
   deprivation: SchoolDeprivation | null;
   finance: SchoolFinance | null;
+  /**
+   * Optional so an older backend, which does not send the key at all, still
+   * typechecks. Null means the school has no published destination data;
+   * either way the sections simply do not render.
+   */
+  destinations?: SchoolDestinations | null;
 }
 
 export interface ComparisonData {