fix some typescript errors

website/src/lib/components/ModeSwitch.svelte

@@ -3,11 +3,18 @@
     import { Moon, Sun } from '@lucide/svelte';
     import { mode, setMode } from 'mode-watcher';
     import { i18n } from '$lib/i18n.svelte';
+
+    let {
+        class: className = '',
+    }: {
+        class?: string;
+    } = $props();
 </script>
 
 <Button
     variant="ghost"
     size="icon"
+    class={className}
     onclick={() => {
         setMode(mode.current === 'light' ? 'dark' : 'light');
     }}