Mijn aanvragen (F2): document preview/download on completed uploads

Re-opening a Concept wizard now lets the user preview/download what they already
uploaded (PRD 0001 goal 2).

- document-chip: optional previewUrl input → a "Voorbeeld / Download" link (opens
  the stored bytes; server serves inline for pdf/image, attachment otherwise).
- previewUrlFor callback threaded document-upload → document-category → single-upload
  (which builds the URL from a completed upload's documentId). Keeps URL-building out
  of the presentational atoms.
- registratie + herregistratie wizards supply previewUrlFor via UploadAdapter.contentUrl,
  returning undefined for dev-simulation `demo-*` ids (no stored bytes → no link).
- Story: DocumentChip/WithPreview.

Gates green: vitest 128, lint, ng build, check:tokens; backend dotnet 56.
(build-storybook has a pre-existing Compodoc/$localize issue in untouched files.)

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

src/app/shared/ui/upload/document-upload/document-upload.component.ts

@@ -25,6 +25,7 @@ import { UploadStatusBannerComponent } from '../upload-status-banner/upload-stat
           [uploads]="uploadsFor(c.categoryId)"
           [channel]="channelFor(c.categoryId)"
           [rejection]="state().rejections[c.categoryId]"
+          [previewUrlFor]="previewUrlFor()"
           (fileSelected)="fileSelected.emit({ categoryId: c.categoryId, files: $event })"
           (removeUpload)="removeUpload.emit($event)"
           (retryUpload)="retryUpload.emit($event)"
@@ -36,6 +37,8 @@ import { UploadStatusBannerComponent } from '../upload-status-banner/upload-stat
 })
 export class DocumentUploadComponent {
   state = input.required<UploadState>();
+  /** Optional: builds a preview/download URL for a completed upload's documentId. */
+  previewUrlFor = input<(documentId: string) => string | undefined>();
 
   fileSelected = output<{ categoryId: string; files: File[] }>();
   removeUpload = output<string>();