implemented storing of user's language as well as loading

frontend/src/App.svelte

@@ -1,5 +1,4 @@
 <script>
-    import { onMount } from 'svelte';
     import { Router, Route } from 'svelte-tiny-router';
 
     import { loadTranslation } from './translations.svelte.js';
@@ -39,10 +38,11 @@
 
     let translations_ready = $state(false);
 
-    onMount(async () => {
-        await loadTranslation('de','Login');
+    async function load(){
+        loadTheme(user.theme);
+        await loadTranslation(user.language?user.language:'de');
         translations_ready = true;
-    });
+    }
 
     function loadTheme(name){
         if (!name) return;
@@ -56,7 +56,7 @@
         next();
     }
 
-    $effect(() => loadTheme(user.theme));
+    $effect(load);
 </script>
 
 {#if translations_ready }