adds shadcn, removes skeleton, implements button after styleguide

src/lib/components/ui/card/card-header.svelte

@@ -0,0 +1,23 @@
+<script lang="ts">
+	import { cn, type WithElementRef } from "$lib/utils.js";
+	import type { HTMLAttributes } from "svelte/elements";
+
+	let {
+		ref = $bindable(null),
+		class: className,
+		children,
+		...restProps
+	}: WithElementRef<HTMLAttributes<HTMLDivElement>> = $props();
+</script>
+
+<div
+	bind:this={ref}
+	data-slot="card-header"
+	class={cn(
+		"gap-1 rounded-t-xl px-4 group-data-[size=sm]/card:px-3 [.border-b]:pb-4 group-data-[size=sm]/card:[.border-b]:pb-3 group/card-header @container/card-header grid auto-rows-min items-start has-data-[slot=card-action]:grid-cols-[1fr_auto] has-data-[slot=card-description]:grid-rows-[auto_auto]",
+		className
+	)}
+	{...restProps}
+>
+	{@render children?.()}
+</div>