use runes mode, allow switching locale without js

Signed-off-by: ngn <ngn@ngn.tf>

app/src/components/head.svelte

@@ -2,7 +2,7 @@
   import { locale } from "$lib/locale.js";
   import api from "$lib/api.js";
 
-  export let desc, title;
+  let { desc, title } = $props();
 </script>
 
 <svelte:head>