fix: keep the user menu and the bell in the header slot

With two elements in the signed-in branch, neither was projected into the
shell's user slot.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/web/src/app/app.ts

@@ -46,8 +46,11 @@ import { NotificationsBell } from '@task-stream/web/tracker/presenters';
         Explorar
       </a>
       @if (auth.isAuthenticated()) {
-        <ts-notifications-bell shellUser />
-        <ts-user-menu shellUser />
+        <!-- One projectable node per @if branch, or neither reaches the slot. -->
+        <ng-container shellUser>
+          <ts-notifications-bell />
+          <ts-user-menu />
+        </ng-container>
       } @else if (auth.settled() && !onLogin()) {
         <a shellUser class="ts-nav-link ts-nav-link--cta" routerLink="/login"
           >Iniciar sesión</a