feat: restructure settings menu + add automation/agents to topbar

TopBar:
- Add Automation and Agenten to user dropdown menu

Settings restructure:
- Stammdaten: Firmendaten, Adressen (CRUD), Konten (CRUD), Sonstige Daten
- Nutzerverwaltung: Benutzer, Rollen, Gruppen as tabs
- System: Menü, Theme, Plugins as tabs
- Reduce nav items from 15+ to 8
- Add end prop to all settings NavLinks

frontend/src/components/layout/TopBar.tsx

@@ -8,7 +8,7 @@ import { useLogout } from '@/api/hooks';
 import { Avatar } from '@/components/ui/Avatar';
 import { SearchDropdown } from '@/components/shared/SearchDropdown';
 import { SuggestionBadge } from '@/components/ai/SuggestionBadge';
-import { Building, ChevronDown, Menu } from 'lucide-react';
+import { Building, ChevronDown, Menu, Zap, Bot } from 'lucide-react';
 
 export function TopBar() {
   const { t } = useTranslation();
@@ -116,6 +116,22 @@ export function TopBar() {
               >
                 {t('topbar.settings')}
               </button>
+              <button
+                onClick={() => { setUserMenuOpen(false); navigate('/automation'); }}
+                className="w-full text-left px-3 py-2 text-sm hover:bg-secondary-50 min-h-touch focus:outline-none focus-visible:ring-2 focus-visible:ring-primary-500 flex items-center gap-2"
+                role="menuitem"
+              >
+                <Zap className="w-4 h-4" aria-hidden="true" strokeWidth={2} />
+                {t('nav.automation', 'Automation')}
+              </button>
+              <button
+                onClick={() => { setUserMenuOpen(false); navigate('/agents'); }}
+                className="w-full text-left px-3 py-2 text-sm hover:bg-secondary-50 min-h-touch focus:outline-none focus-visible:ring-2 focus-visible:ring-primary-500 flex items-center gap-2"
+                role="menuitem"
+              >
+                <Bot className="w-4 h-4" aria-hidden="true" strokeWidth={2} />
+                {t('nav.agents', 'Agenten')}
+              </button>
               <button
                 onClick={() => { setUserMenuOpen(false); navigate('/audit-log'); }}
                 className="w-full text-left px-3 py-2 text-sm hover:bg-secondary-50 min-h-touch focus:outline-none focus-visible:ring-2 focus-visible:ring-primary-500"