clients page: make add form a modal

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

@@ -0,0 +1,13 @@
+<script lang="ts">
+	import type { HTMLAttributes } from "svelte/elements";
+	import { cn } from "$lib/utils.js";
+
+	type $$Props = HTMLAttributes<HTMLDivElement>;
+
+	let className: $$Props["class"] = undefined;
+	export { className as class };
+</script>
+
+<div class={cn("flex flex-col space-y-1.5 text-center sm:text-left", className)} {...$$restProps}>
+	<slot />
+</div>