feat(VirtualList): add isLoading prop

src/shared/ui/VirtualList/VirtualList.svelte

@@ -101,13 +101,25 @@ interface Props {
      * @template T - The type of items in the list
      */
     children: Snippet<
-        [{ item: T; index: number; isFullyVisible: boolean; isPartiallyVisible: boolean; proximity: number }]
+        [
+            {
+                item: T;
+                index: number;
+                isFullyVisible: boolean;
+                isPartiallyVisible: boolean;
+                proximity: number;
+            },
+        ]
     >;
     /**
      * Whether to use the window as the scroll container.
      * @default false
      */
     useWindowScroll?: boolean;
+    /**
+     * Flag to show loading state
+     */
+    isLoading?: boolean;
 }
 
 let {
@@ -120,6 +132,7 @@ let {
     onNearBottom,
     children,
     useWindowScroll = false,
+    isLoading = false,
 }: Props = $props();
 
 // Reference to the ScrollArea viewport element for attaching the virtualizer