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/shared/ui/upload/document-category/document-category.component.ts

@@ -50,6 +50,8 @@ import { SingleUploadComponent } from '../single-upload/single-upload.component'
       <div class="uploads">
         @for (u of uploads(); track u.localId) {
           <app-single-upload
+            animate.enter="app-item-enter"
+            animate.leave="app-item-leave"
             [upload]="u"
             [previewUrlFor]="previewUrlFor()"
             (remove)="onRemove(u)"