feat(beheer): stamdata deletion protection — CI referential gate + editor expire/warn

CI gate (authoritative): generalize the dangling-reference test in StamdataValidationTests
into a declared, extensible reference list ("every declared reference into a stamdata key
resolves against the currently-valid stamdata"), starting with Diploma.Opleiding →
professions.program. Removing/renaming a referenced program, or expiring it while current
data still references it, fails the PR build (ADR-0004). Editor (fast feedback): confirm
before delete (warns a referenced row fails CI) and, for temporal tables, a "Sluiten per
vandaag" action that closes validity (geldigTot) — steering to expire over hard delete.

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

src/app/beheer/ui/stamdata-table-editor/stamdata-table-editor.component.ts

@@ -145,10 +145,15 @@ interface DisplayRow {
             }
             <td>
               @if (!previewing()) {
+                @if (table().temporal) {
+                  <app-button variant="subtle" (click)="onExpire(item.index)">{{
+                    expireLabel
+                  }}</app-button>
+                }
                 <app-button
                   variant="subtle"
                   [attr.aria-label]="removeLabel"
-                  (click)="rowRemoved.emit(item.index)"
+                  (click)="onRemove(item.index)"
                   >{{ removeLabel }}</app-button
                 >
               }
@@ -234,6 +239,21 @@ export class StamdataTableEditorComponent {
   protected previewNote = $localize`:@@beheer.previewNote:Voorbeeld: alleen de rijen die op deze datum geldig zijn. Bewerken staat uit.`;
   protected actionsLabel = $localize`:@@beheer.actions:Acties`;
   protected removeLabel = $localize`:@@beheer.remove:Verwijderen`;
+  protected expireLabel = $localize`:@@beheer.expire:Sluiten per vandaag`;
+  private removeConfirm = $localize`:@@beheer.removeConfirm:Rij verwijderen? Als andere gegevens ernaar verwijzen, faalt de build-controle (CI). Bij een tabel met een geldigheidsperiode kunt u de rij beter sluiten (geldig tot) in plaats van verwijderen.`;
+
+  /** Deletions can orphan a reference (the CI gate catches it); confirm first (WP-48). */
+  protected onRemove(index: number) {
+    if (confirm(this.removeConfirm)) this.rowRemoved.emit(index);
+  }
+
+  /** Steer temporal tables toward expiring (close the validity per today) over hard delete —
+      preserves history and can't orphan a reference that was valid earlier (WP-48). */
+  protected onExpire(index: number) {
+    const col = this.table().columns.find((c) => /geldigtot/i.test(c.name));
+    if (col) this.cellEdited.emit({ row: index, column: col.name, value: this.today });
+  }
+  private today = new Date().toISOString().slice(0, 10);
   protected undoLabel = $localize`:@@beheer.undo:Ongedaan maken`;
   protected redoLabel = $localize`:@@beheer.redo:Opnieuw uitvoeren`;
   protected addRowLabel = $localize`:@@beheer.addRow:Rij toevoegen`;