refactor(channels): apply .app-scrollbar to favorites and recent views

Round out the channel-list-container views so the favorites and recent
panels get the same persistent scrollbar gutter and themed thumb as the
all-channels and groups views.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Entire-Checkpoint: 2301533420c9

libs/ui/components/src/lib/channel-list-container/favorites-view/favorites-view.component.html

@@ -1,5 +1,5 @@
 <div
-    class="channel-list"
+    class="channel-list app-scrollbar"
     cdkDropList
     [cdkDropListDisabled]="hasSearchTerm()"
     (cdkDropListDropped)="onDrop($event)"

libs/ui/components/src/lib/channel-list-container/recent-view/recent-view.component.html

@@ -1,4 +1,4 @@
-<div class="channel-list" id="recent-list">
+<div class="channel-list app-scrollbar" id="recent-list">
     @if (enrichedRecentItems().length > 0) {
         @for (
             item of enrichedRecentItems();