refactor: remove Karriere link from header navigation

app/[locale]/layout.tsx

@@ -100,10 +100,6 @@ export default async function Layout(props: {
       label: safeLocale === 'de' ? 'Referenzen' : 'References',
       url: `/${safeLocale}/referenzen`
     },
-    { 
-      label: safeLocale === 'de' ? 'Karriere' : 'Careers', 
-      url: `/${safeLocale}/${await mapFileSlugToTranslated('karriere', safeLocale)}` 
-    },
     { 
       label: safeLocale === 'de' ? 'Messen' : 'Events', 
       url: `/${safeLocale}/${await mapFileSlugToTranslated('messen', safeLocale)}`