feat(portal-shell): collapse accessibility routes into one i18n-marked route

Continue ADR-0019: replace the `/accessibility` + `/accessibilite`
twin routes with a single canonical `/accessibility` path whose
content is i18n-marked in templates. The per-locale build (en/fr)
already inlines the right copy — the route data + `copy()` service
indirection is no longer needed.

What changes:

- `AccessibilityStatement` loses its `ActivatedRoute` injection, its
  `Lang` discriminator and the `COPY` lookup table. The component is
  now a plain shell over the template.
- `accessibility.html` carries the title + intro + status panel
  strings as `i18n="@@page.accessibility.*"` markers; six new
  trans-units in `messages.fr.xlf` provide the French copy
  (verbatim from the old `COPY.fr` block, kept identical so the page
  reads the same in FR).
- `app.routes.ts` declares the single canonical route and keeps
  `/accessibilite` as a `redirectTo: 'accessibility'` for backward
  compatibility with existing bookmarks. Drops the `data.lang`
  payload — no longer consumed.
- `footer.html` collapses the dual link (`Accessibility` /
  `Accessibilité`) into one i18n-marked link
  (`@@footer.accessibilityLink`). EN bundle reads "Accessibility
  statement"; FR bundle reads "Déclaration d'accessibilité".

The path stays in English across both locales for now
(`/{en,fr}/accessibility`). Translating route segments
(`/fr/declaration-d-accessibilite`) is a future refinement that needs
either a custom URL serializer or per-locale route trees — not worth
the complexity at this scale.

Specs:

- `accessibility.spec.ts` loses the `lang`-based tests and asserts
  on the rendered EN source content + the amber-panel structure
  (specs run in the source locale).
- `footer.spec.ts` asserts on the single accessibility link and the
  absence of the historical `/accessibilite` href.

Test plan / verification:

- 35/35 specs pass (was 36; one obsolete `lang` fallback test
  removed).
- Production build emits both locales; FR chunk contains "Statut",
  "Déclaration", FR intro/panel bodies, and no leftover English from
  the swept strings.

apps/portal-shell/src/app/app.routes.ts

@@ -1,9 +1,9 @@
 import { Route } from '@angular/router';
 
 // Tab titles per route — marked with `$localize` so each locale's
-// bundle ships its own. The `/accessibility` and `/accessibilite`
-// pair shares a title key; the upcoming route fusion (per ADR-0019)
-// collapses them to a single localised route.
+// bundle ships its own. The accessibility statement now lives at the
+// single canonical path `/accessibility` (per ADR-0019, replacing the
+// previous `/accessibility` + `/accessibilite` pair).
 const homeTitle = $localize`:@@route.home.title:APF Portal`;
 const accessibilityTitle = $localize`:@@route.accessibility.title:Accessibility statement · APF Portal`;
 
@@ -14,21 +14,21 @@ export const appRoutes: Route[] = [
     loadComponent: () => import('./pages/home/home').then((m) => m.Home),
     title: homeTitle,
   },
-  // RGAA + ADR-0016: the accessibility statement must be reachable
-  // from both locales' canonical paths. Same component, content
-  // driven by the `lang` route data property.
+  // RGAA + ADR-0016: the accessibility statement is reachable from
+  // `/accessibility` in every locale. Content is i18n-marked so the
+  // per-locale bundle ships the right copy automatically.
   {
     path: 'accessibility',
     loadComponent: () =>
       import('./pages/accessibility/accessibility').then((m) => m.AccessibilityStatement),
-    data: { lang: 'en' },
     title: accessibilityTitle,
   },
+  // Backward-compat: the historical French path redirects to the
+  // canonical one. Bookmarks and existing inbound links keep working.
+  // Drops out of the codebase once analytics confirm no traffic.
   {
     path: 'accessibilite',
-    loadComponent: () =>
-      import('./pages/accessibility/accessibility').then((m) => m.AccessibilityStatement),
-    data: { lang: 'fr' },
-    title: accessibilityTitle,
+    redirectTo: 'accessibility',
+    pathMatch: 'full',
   },
 ];