Rijkshuisstijl restyle + wizard fixes

Chrome: two-tier Rijksoverheid header (white brand bar + lint-blue
breadcrumb bar, route-driven), dark multi-column footer, white page
surface. Session shown via a shared SESSION_PORT token (keeps shared/
free of the auth context).

Overview ("Mijn overzicht") rebuilt to the NL Design System #392 pattern:
side-nav + "Wat moet ik regelen" task list (derived) + "Mijn registratie"
cards. New shared components: card, task-list, side-nav; pure
tasksFromProfile (+spec).

Wizards: grey form panel, connected numbered stepper, form-field
"(verplicht)" markers + styled description/error, full-width inputs.
Propagated to login, detail, change-request, address-fields.

Bug fixes:
- wizard-shell: add FormsModule so NgForm intercepts submit (wizards now
  advance; no native GET leaking choices into the URL).
- wizard-shell: error-summary links focus the field instead of navigating
  (a fragment href resolved against <base href="/"> reloaded to "/" and
  bounced to login).
- wizard-shell: error-summary focus only on the rising edge, so typing
  while errors are shown no longer scrolls the page up.

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

src/app/registratie/ui/change-request-form/change-request-form.component.ts

@@ -22,12 +22,12 @@ import { ApiClient } from '@shared/infrastructure/api-client';
       <app-alert type="ok">
         Uw adreswijziging is ontvangen (referentie {{ referentie() }}). U ontvangt binnen 5 werkdagen bericht.
       </app-alert>
-      <div style="margin-top:1rem">
+      <div class="app-section">
         <app-button variant="secondary" (click)="dispatch({ tag: 'Reset' })">Nieuwe wijziging doorgeven</app-button>
       </div>
     } @else {
       <app-heading [level]="2">Adreswijziging doorgeven</app-heading>
-      <form (ngSubmit)="onSubmit()" style="max-width:28rem">
+      <form (ngSubmit)="onSubmit()" class="app-form app-form-panel app-section">
         <app-address-fields
           idPrefix="cr"
           [value]="adres()"
@@ -35,14 +35,12 @@ import { ApiClient } from '@shared/infrastructure/api-client';
           (fieldChange)="dispatch({ tag: 'SetField', key: $event.key, value: $event.value })" />
 
         @if (failedError()) {
-          <div style="margin-top:1rem"><app-alert type="error">Het indienen is niet gelukt: {{ failedError() }}</app-alert></div>
+          <app-alert type="error">Het indienen is niet gelukt: {{ failedError() }}</app-alert>
         }
 
-        <div style="margin-top:1rem">
-          <app-button type="submit" variant="primary" [disabled]="state().tag === 'Submitting'">
-            {{ state().tag === 'Submitting' ? 'Bezig met indienen…' : 'Wijziging indienen' }}
-          </app-button>
-        </div>
+        <app-button type="submit" variant="primary" [disabled]="state().tag === 'Submitting'">
+          {{ state().tag === 'Submitting' ? 'Bezig met indienen…' : 'Wijziging indienen' }}
+        </app-button>
       </form>
     }
   `,