Mijn aanvragen: list enter/leave animations + 204 null-body fix

- animate.enter/leave on aanvraag cards and upload rows (native Angular, no @angular/animations)
- reduced-motion: skip animation → instant removal
- api-client: null-body statuses (204/205/304) must pass null to Response()

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

src/app/registratie/ui/dashboard.page.ts

@@ -39,7 +39,7 @@ import { tasksFromProfile } from '@registratie/domain/tasks';
               <app-heading [level]="2" i18n="@@dashboard.mijnAanvragen">Mijn aanvragen</app-heading>
               <div class="app-stack app-section">
                 @for (a of aanvragen(); track a.id) {
-                  <app-aanvraag-block [aanvraag]="a" (resume)="resume(a)" (cancel)="cancelAanvraag(a)" />
+                  <app-aanvraag-block animate.enter="app-item-enter" animate.leave="app-item-leave" [aanvraag]="a" (resume)="resume(a)" (cancel)="cancelAanvraag(a)" />
                 }
               </div>
             </section>