fix(scrollbar): make .app-scrollbar override component-scoped overflow

Two issues kept the scrollbar invisible on the global Favorites and
Recently viewed live-tv lists:

1. The wrong files. The visible Favorites/Recent pages render through
   <app-global-favorites-list> from portal/shared/ui (and the
   workspace-shell variant), not the channel-list-container's tabs.
   Apply .app-scrollbar to both of those components.

2. Specificity. Component CSS gets an Angular [_ngcontent-xxx]
   attribute selector, so `.nav-list { overflow-y: auto }` resolves to
   (0,2,0) — same as the doubled `.app-scrollbar.app-scrollbar` and
   wins on source order (component CSS loads after globals). Mark
   overflow-y: scroll !important on the utility so the contract holds:
   applying .app-scrollbar always reserves the gutter.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Entire-Checkpoint: 8ae011808369

libs/workspace/shell/feature/src/lib/global-favorites/global-favorites-list.component.html

@@ -13,7 +13,7 @@
     </mat-form-field>
 </div>
 
-<div class="nav-list" cdkDropList (cdkDropListDropped)="onDrop($event)">
+<div class="nav-list app-scrollbar" cdkDropList (cdkDropListDropped)="onDrop($event)">
     @if (enrichedChannels().length === 0) {
         <div class="empty-state">
             <mat-icon class="empty-icon">star_border</mat-icon>