fix: replace remaining "New dashboards" with "All dashboards" in add form

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

Author: gugu

frontend/src/app/components/users/cedar-policy-list/cedar-policy-list.component.html

@@ -100,7 +100,7 @@
             <mat-form-field *ngIf="needsDashboard" appearance="outline" class="policy-field">
                 <mat-label>Dashboard</mat-label>
                 <mat-select [(ngModel)]="newDashboardId" [ngModelOptions]="{standalone: true}">
-                    <mat-option value="__new__">New dashboards</mat-option>
+                    <mat-option value="*">All dashboards</mat-option>
                     <mat-option *ngFor="let dashboard of availableDashboards" [value]="dashboard.id">
                         {{ dashboard.name }}
                     </mat-option>