resolve issues with new features

frontend/src/components/shared/Sidebar.tsx

@@ -135,7 +135,7 @@ function Sidebar({ mobileOpen, onMobileClose }: SidebarProps) {
   const vehicleSubItems: SubItem[] = useMemo(
     () =>
       (vehicleList ?? []).map((v) => ({
-        text: v.kurzname ?? v.bezeichnung,
+        text: v.bezeichnung ?? v.kurzname,
         path: `/fahrzeuge/${v.id}`,
       })),
     [vehicleList],
@@ -196,7 +196,7 @@ function Sidebar({ mobileOpen, onMobileClose }: SidebarProps) {
                 >
                   <ListItemButton
                     selected={isActive}
-                    onClick={() => handleNavigation(hasSubItems ? item.subItems![0].path : item.path)}
+                    onClick={() => handleNavigation(item.path)}
                     aria-label={`Zu ${item.text} navigieren`}
                     sx={{
                       justifyContent: sidebarCollapsed ? 'center' : 'initial',