feat(design): re-theme to CIBG Huisstijl (Bootstrap 5.2), replacing RHC/Utrecht

The portal now adheres to the CIBG design system (designsystem.cibg.nl) — a customized
Bootstrap 5.2 build — replacing the Rijkshuisstijl-Community / Utrecht theme. See ADR-0003.

- Vendor @cibg/huisstijl@3.22.0 under public/cibg-huisstijl/, loaded via a <link> in
  index.html (Storybook serves it via staticDirs). Drop the two @rijkshuisstijl-community deps.
- Token bridge in styles.scss: redefine the app's ~54 --rhc-* tokens onto CIBG/--bs-* values,
  so components keep referencing tokens (no 300+ site rewrite). System-font stack; licensed
  RO/Rijks text fonts intentionally not shipped.
- Re-skin every shared atom to Bootstrap/CIBG classes (btn, form-control, form-check-*,
  table, breadcrumb, …) keeping their input() APIs. alert is hand-rolled (CIBG drops .alert);
  local .card/.badge renamed to avoid Bootstrap collisions.
- Domain pages: drop stray rhc-*/utrecht-* classes; registration-table → table table-striped.

Verified: build green, check:tokens OK, lint clean, 174 tests pass, build-storybook OK,
and the served build loads the vendored CSS (200, .btn-primary present).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.storybook/preview.ts

@@ -5,12 +5,10 @@ import docJson from '../documentation.json';
 setCompodocJson(docJson);
 
 const preview: Preview = {
-  // Apply the Rijkshuisstijl theme classes around every story so the design
-  // tokens cascade (global component CSS comes from the app's build target).
+  // CIBG/Bootstrap styles bare elements — no theme wrapper class needed; just pad.
+  // The token bridge lives in styles.scss (loaded via the app build target).
   decorators: [
-    componentWrapperDecorator(
-      (story) => `<div class="rhc-theme lintblauw utrecht-document" style="padding:1.5rem">${story}</div>`
-    ),
+    componentWrapperDecorator((story) => `<div style="padding:1.5rem">${story}</div>`),
   ],
   parameters: {
     layout: 'padded',