Fix template error on publication detail page when data is loading

Added safe navigation operator to publication?.pubKey in delete button
text to prevent TypeError when publication is still undefined.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jcschaff

webapp-ng/src/app/components/publication-detail/publication-detail.component.html

@@ -5,4 +5,4 @@ <h4>Loading publication...</h4>
 </ng-template><br/>
 
 <app-publication-edit [publication]="publication" (save)="saveUpdatedPublication($event)" (cancel)="cancel()" (published)="refreshPublication()"></app-publication-edit>
-<button mat-raised-button color="warn" (click)="deletePublication(publication)" [disabled]="!publication">Delete Publication {{publication.pubKey}}</button>
+<button mat-raised-button color="warn" (click)="deletePublication(publication)" [disabled]="!publication">Delete Publication {{publication?.pubKey}}</button>