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.

server/routes.js

@@ -54,6 +54,39 @@ export function setupRoutes(app, __dirname) {
   app.get('/api/health', (req, res) => {
     res.json({ status: 'ok', timestamp: new Date().toISOString() });
   });
+
+  app.post('/api/logout', (req, res) => {
+    try {
+      const sessionId = req.sessionID;
+      const clientsMap = getClientsMap();
+      const client = clientsMap.get(sessionId);
+
+      if (client?.socket) {
+        try {
+          client.socket.disconnect(true);
+        } catch (error) {
+          console.warn('Logout: Socket konnte nicht sauber getrennt werden:', error);
+        }
+      }
+
+      if (sessionId) {
+        clientsMap.delete(sessionId);
+      }
+
+      req.session.destroy((error) => {
+        if (error) {
+          console.error('Logout: Session konnte nicht zerstört werden:', error);
+          return res.status(500).json({ success: false });
+        }
+
+        res.clearCookie('connect.sid');
+        res.json({ success: true });
+      });
+    } catch (error) {
+      console.error('Logout-Fehler:', error);
+      res.status(500).json({ success: false });
+    }
+  });
   
   // Bild-Upload-Endpoint
   app.post('/api/upload-image', upload.single('image'), (req, res) => {
@@ -385,4 +418,3 @@ export function setupRoutes(app, __dirname) {
     }
   });
 }
-