feat: start page after login with workspace grid, login redirect to /start

frontend/src/routes/index.tsx

@@ -1,6 +1,7 @@
 import React, { Suspense } from 'react';
 import { createBrowserRouter, RouterProvider } from 'react-router-dom';
 import { AppShell } from '@/components/layout/AppShell';
+import { StartLayout } from '@/components/layout/StartLayout';
 import { ProtectedRoute } from './ProtectedRoute';
 import { ProtectedRoute as PermissionRoute } from '@/components/common/ProtectedRoute';
 import { LoginPage } from '@/pages/Login';
@@ -65,6 +66,7 @@ const SettingsWebhooksPage = React.lazy(() => import('@/pages/SettingsWebhooks')
 const SettingsBackupPage = React.lazy(() => import('@/pages/SettingsBackup').then(m => ({ default: m.SettingsBackupPage })));
 const SettingsRechtePage = React.lazy(() => import('@/pages/SettingsRechte').then(m => ({ default: m.SettingsRechtePage })));
 const NoAccessPage = React.lazy(() => import('@/pages/NoAccessPage').then(m => ({ default: m.NoAccessPage })));
+const StartPage = React.lazy(() => import('@/pages/StartPage').then(m => ({ default: m.StartPage })));
 
 /** Centered spinner fallback for lazy-loaded routes */
 function PageLoader() {
@@ -125,6 +127,16 @@ const router = createBrowserRouter([
     path: '/kein-zugriff',
     element: <ErrorBoundary>{withSuspense(<NoAccessPage />)}</ErrorBoundary>,
   },
+  {
+    element: (
+      <ProtectedRoute>
+        <StartLayout />
+      </ProtectedRoute>
+    ),
+    children: [
+      { path: '/start', element: withSuspense(<StartPage />) },
+    ],
+  },
   {
     element: (
       <ProtectedRoute>
@@ -132,7 +144,7 @@ const router = createBrowserRouter([
       </ProtectedRoute>
     ),
     children: [
-      { path: '/', element: withSuspense(<DashboardPage />) },
+      { path: '/', element: <Navigate to="/start" replace /> },
       { path: '/dashboard', element: withSuspense(<DashboardPage />) },
       { path: '/contacts', element: <PermissionRoute permission="contacts:read">{withSuspense(<ContactsListPage />)}</PermissionRoute> },
       { path: '/contacts/:id', element: <PermissionRoute permission="contacts:read">{withSuspense(<ContactDetailPage />)}</PermissionRoute> },