Light mode update

frontend/src/components/CornerMenu.svelte

@@ -1,10 +1,16 @@
 <script>
     import { extraMenuLinks } from '../lib/menu';
+    import { theme, toggleTheme } from '../lib/theme';
 
     let open = false;
 
-    const baseLinks = [
+    $: themeLink = $theme === 'dark'
+        ? { label: '☀️ Light Mode', action: toggleTheme, keepOpen: true, title: 'Switch to the light theme' }
+        : { label: '🌙 Dark Mode', action: toggleTheme, keepOpen: true, title: 'Switch to the dark theme' };
+
+    $: baseLinks = [
         { label: '📖 Rules', href: '/rules', external: true, title: 'Open the rulebook in a new tab' },
+        themeLink,
     ];
 
     $: links = [...$extraMenuLinks, ...baseLinks];
@@ -29,7 +35,7 @@
                     <button
                         class="menu-item"
                         title={link.title}
-                        on:click={() => { open = false; link.action(); }}
+                        on:click={() => { if (!link.keepOpen) open = false; link.action(); }}
                     >{link.label}</button>
                 {:else}
                     <a