refactor: drop redundant optional chaining on checkSum

file is guaranteed by *ngFor and checkSum is truthy inside the *ngIf
guard, so use plain file.checkSum / file.checkSum.value to match the
surrounding template style.

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

Author: jr-rk

src/app/item-page/full/field-components/file-section/full-file-section.component.html

@@ -23,9 +23,9 @@ <h3 class="h5 simple-view-element-header">{{"item.page.filesection.original.bund
                             <dd class="col-md-8">{{(file.sizeBytes) | dsFileSize }}</dd>
 
 
-                          <ng-container *ngIf="file?.checkSum">
+                          <ng-container *ngIf="file.checkSum">
                             <dt class="col-md-4">{{"item.page.filesection.checksum" | translate}}</dt>
-                            <dd class="col-md-8">{{ file?.checkSum?.value }}</dd>
+                            <dd class="col-md-8">{{ file.checkSum.value }}</dd>
                           </ng-container>
 
                           <ng-container *ngIf="file.hasMetadata('dc.description')">
@@ -66,9 +66,9 @@ <h3 class="h5 simple-view-element-header">{{"item.page.filesection.license.bundl
                             <dt class="col-md-4">{{"item.page.filesection.size" | translate}}</dt>
                             <dd class="col-md-8">{{(file.sizeBytes) | dsFileSize }}</dd>
 
-                          <ng-container *ngIf="file?.checkSum">
+                          <ng-container *ngIf="file.checkSum">
                             <dt class="col-md-4">{{"item.page.filesection.checksum" | translate}}</dt>
-                            <dd class="col-md-8">{{ file?.checkSum?.value }}</dd>
+                            <dd class="col-md-8">{{ file.checkSum.value }}</dd>
                           </ng-container>