fix(standorte): fix layout and navigation structure

components/layout/Header.tsx

@@ -11,6 +11,7 @@ export interface NavLink {
   label: string;
   url: string;
   children?: NavLink[];
+  isGroupLabel?: boolean;
 }
 
 interface HeaderProps {
@@ -218,11 +219,20 @@ function NavItem({ link, currentLocale, pathname, isSolidMode }: { link: NavLink
               {/* Top glowing accent line */}
               <div className="absolute top-0 left-0 w-full h-[2px] bg-gradient-to-r from-transparent via-primary to-transparent opacity-70" />
               
-              {link.children.map((child) => {
+              {link.children.map((child, idx) => {
                 const childUrl = child.url.startsWith('/') && !child.url.match(/^\/(en|de)/) 
                   ? `/${currentLocale}${child.url}` 
                   : child.url;
                 const isChildActive = pathname === childUrl;
+                
+                if (child.isGroupLabel) {
+                  return (
+                    <div key={`group-${idx}`} className={`mt-2 mb-1 px-4 text-[11px] font-bold uppercase tracking-wider ${isSolidMode ? 'text-neutral-400' : 'text-neutral-500'}`}>
+                      {child.label}
+                    </div>
+                  );
+                }
+
                 return (
                   <TransitionLink
                     key={child.url}