style: format frontend, docs and skills with prettier; add .prettierignore

One-time prettier --write so the new format:check CI gate starts green.
.prettierignore excludes generated (api-client.ts, documentation.json),
vendored (public/cibg-huisstijl), and backend (dotnet format owns it).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app/shared/ui/upload/upload-status-banner/upload-status-banner.component.ts

@@ -19,5 +19,7 @@ export class UploadStatusBannerComponent {
   message = input.required<string>();
   type = input<BannerType>('info');
 
-  protected readonly alertType = computed<AlertType>(() => (this.type() === 'info' ? 'info' : this.type()));
+  protected readonly alertType = computed<AlertType>(() =>
+    this.type() === 'info' ? 'info' : this.type(),
+  );
 }