Enhance UI and functionality across multiple components

- Updated styles in style.css to improve overall design consistency and introduced CSS variables for better theming.
- Refined ChatWindow.vue with improved no-conversation styling and adjusted image borders for a cleaner look.
- Enhanced HistoryView.vue and InboxView.vue with new panel styles for better user experience and readability.
- Revamped LoginForm.vue to provide a more engaging user interface with a landing page layout and cookie-based profile persistence.
- Improved MenuBar.vue and SearchView.vue with active state indicators and refined item displays for better navigation.
- Added logout functionality in chat store and server routes to manage user sessions effectively.
- Introduced a new mockup view route for design previews.

These changes collectively enhance the user experience and visual appeal of the application.

client/src/router/index.js

@@ -1,6 +1,7 @@
 import { createRouter, createWebHistory } from 'vue-router';
 import ChatView from '../views/ChatView.vue';
 import PartnersView from '../views/PartnersView.vue';
+import MockupView from '../views/MockupView.vue';
 
 const routes = [
   {
@@ -22,6 +23,16 @@ const routes = [
       description: 'Unsere Partner und befreundete Seiten. Entdecke weitere interessante Angebote und Communities.',
       keywords: 'Partner, Links, befreundete Seiten, Community'
     }
+  },
+  {
+    path: '/mockup-redesign',
+    name: 'mockup-redesign',
+    component: MockupView,
+    meta: {
+      title: 'Design Mockup - SingleChat',
+      description: 'Visuelle Vorschau des geplanten Design-Refreshs fuer SingleChat.',
+      keywords: 'SingleChat, Mockup, Design, Redesign, Vorschau'
+    }
   }
 ];
 
@@ -76,4 +87,3 @@ router.beforeEach((to, from, next) => {
 });
 
 export default router;
-