feat: add dashboard page with stats, quick actions, recent vehicles, update navigation and login redirect

frontend/app/(auth)/login/page.tsx

@@ -41,7 +41,7 @@ function LoginForm() {
       const tokens = await apiLogin(email, password);
       setTokens(tokens);
       showToast(t('login.success'), 'success');
-      router.push('/de/fahrzeuge');
+      router.push('/de/dashboard');
     } catch (err) {
       const message = (err as any)?.error?.message || t('login.error.invalidCredentials');
       showToast(message, 'error');

frontend/app/[locale]/dashboard/page.tsx

@@ -0,0 +1,5 @@
+import { Dashboard } from '@/components/Dashboard';
+
+export default function DashboardPage() {
+  return <Dashboard />;
+}

frontend/app/[locale]/page.tsx

@@ -0,0 +1,5 @@
+import { Dashboard } from '@/components/Dashboard';
+
+export default function LocaleHomePage() {
+  return <Dashboard />;
+}