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>

src/app/shared/ui/form-field/form-field.component.ts

@@ -12,16 +12,16 @@ import { Component, booleanAttribute, input } from '@angular/core';
     .error{color:var(--rhc-color-foreground-default);font-weight:var(--rhc-text-font-weight-semi-bold);margin-block-start:var(--rhc-space-max-sm);border-inline-start:var(--rhc-border-width-md) solid var(--rhc-color-rood-500);padding-inline-start:var(--rhc-space-max-md)}
   `],
   template: `
-    <div class="rhc-form-field utrecht-form-field" [class.utrecht-form-field--invalid]="!!error()">
-      <label class="utrecht-form-label label" [id]="fieldId() + '-label'" [for]="fieldId()">
+    <div class="form-field">
+      <label class="form-label label" [id]="fieldId() + '-label'" [for]="fieldId()">
         {{ label() }}@if (required()) { <span class="req" i18n="@@formField.verplicht">(verplicht)</span> }
       </label>
       @if (description()) {
-        <div class="utrecht-form-field-description desc" [id]="fieldId() + '-desc'">{{ description() }}</div>
+        <div class="form-text desc" [id]="fieldId() + '-desc'">{{ description() }}</div>
       }
       <ng-content />
       @if (error()) {
-        <div class="utrecht-form-field-error-message error" [id]="fieldId() + '-error'" role="alert">{{ error() }}</div>
+        <div class="error" [id]="fieldId() + '-error'" role="alert">{{ error() }}</div>
       }
     </div>
   `,