fix(cibg): wizard fields render as grey fieldset groups

Wizard steps rendered bare .form-group divs, so CIBG's
".form-horizontal fieldset { background:#f1f5f9; margin-bottom:1.25em }"
never matched and inputs showed on white instead of the grey CIBG surface.

Wrap each logical field group per step in a <fieldset> (intake, herregistratie
and registratie wizards); CIBG then gives every group its grey surface with a
1.25em gap between groups. The shell stays group-agnostic (no outer fieldset,
which would hide the white gaps). address-fields already used a <fieldset>.

Adds intake-wizard.component.spec.ts asserting the buitenland step renders its
groups as separate fieldsets (guards against the wrapping being dropped again).

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

src/app/herregistratie/ui/intake-wizard/intake-wizard.component.spec.ts

@@ -0,0 +1,36 @@
+import { provideHttpClient } from '@angular/common/http';
+import { TestBed } from '@angular/core/testing';
+import { describe, expect, it } from 'vitest';
+import { provideApiClient } from '@shared/infrastructure/api-client.provider';
+import { IntakeWizardComponent } from './intake-wizard.component';
+import { IntakeState } from '@herregistratie/domain/intake.machine';
+
+// Regression: wizard steps must render their logical field groups as separate CIBG grey
+// <fieldset> blocks (`.form-horizontal fieldset` ⇒ #f1f5f9, 1.25em gap). If the fieldset
+// wrapping is dropped, the inputs revert to bare white. The buitenland step with
+// buitenlandGewerkt='ja' has two groups (the question + the land/uren follow-up), so it
+// must render ≥2 fieldsets, each holding a form-group.
+const buitenlandJa: IntakeState = {
+  tag: 'Answering',
+  answers: { buitenlandGewerkt: 'ja' },
+  cursor: 0,
+  errors: {},
+  scholingThreshold: 1000,
+};
+
+describe('IntakeWizardComponent', () => {
+  it('renders each field group as its own grey <fieldset>', () => {
+    TestBed.configureTestingModule({
+      providers: [provideHttpClient(), provideApiClient()],
+    });
+    const fixture = TestBed.createComponent(IntakeWizardComponent);
+    fixture.componentInstance.dispatch({ tag: 'Seed', state: buitenlandJa });
+    fixture.detectChanges();
+
+    const fieldsets: HTMLElement[] = Array.from(
+      fixture.nativeElement.querySelectorAll('form.form-horizontal fieldset'),
+    );
+    expect(fieldsets.length).toBeGreaterThanOrEqual(2);
+    fieldsets.forEach((fs) => expect(fs.querySelector('.form-group')).toBeTruthy());
+  });
+});