refactor: migrate shadcn-components to Svelte 5 and TW4 (#551)

Co-authored-by: Elias Schneider <login@eliasschneider.com>

frontend/src/lib/components/ui/calendar/calendar-head-cell.svelte

@@ -2,15 +2,15 @@
 	import { Calendar as CalendarPrimitive } from 'bits-ui';
 	import { cn } from '$lib/utils/style.js';
 
-	type $$Props = CalendarPrimitive.HeadCellProps;
-
-	let className: $$Props['class'] = undefined;
-	export { className as class };
+	let {
+		ref = $bindable(null),
+		class: className,
+		...restProps
+	}: CalendarPrimitive.HeadCellProps = $props();
 </script>
 
 <CalendarPrimitive.HeadCell
-	class={cn('text-muted-foreground w-9 rounded-md text-[0.8rem] font-normal', className)}
-	{...$$restProps}
->
-	<slot />
-</CalendarPrimitive.HeadCell>
+	bind:ref
+	class={cn('text-muted-foreground w-8 rounded-md text-[0.8rem] font-normal', className)}
+	{...restProps}
+/>