feature: add necessary shadcn components for CategoryFilter and Sidebar

src/shared/ui/skeleton/skeleton.svelte

@@ -0,0 +1,18 @@
+<script lang="ts">
+    import { cn, type WithElementRef, type WithoutChildren } from '$shared/utils/shadcn-utils.js';
+import type { HTMLAttributes } from 'svelte/elements';
+
+let {
+    ref = $bindable(null),
+    class: className,
+    ...restProps
+}: WithoutChildren<WithElementRef<HTMLAttributes<HTMLDivElement>>> = $props();
+</script>
+
+<div
+    bind:this={ref}
+    data-slot="skeleton"
+    class={cn('bg-accent animate-pulse rounded-md', className)}
+    {...restProps}
+>
+</div>