Phase 3: Saved Filters UI, Entity History UI, Activity Timeline, API Docs Link

- Saved Filters: SavedFilterBar (dropdown, apply, delete), SaveFilterDialog (name + save)
- Entity History: EntityHistoryPanel (timeline, restore, undo), HistoryDiff (field changes visual)
- Activity Timeline: ActivityTimelinePage (grouped by day, pagination), ActivityFilter (user/entity/action/date)
- API Docs Link: TopBar user menu entry, SettingsSystem Entwickler section (Swagger, ReDoc, OpenAPI)
- Routes: /activity registered
- Menu items: Aktivitäten added to automation plugin manifest

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, Zap, Bot, Layers } from 'lucide-react';
+import { Building, ChevronDown, Menu, Zap, Bot, Layers, Code } from 'lucide-react';
 import { NotificationBell } from '@/components/layout/NotificationBell';
 import { useWindowStore } from '@/store/windowStore';
 
@@ -160,6 +160,17 @@ export function TopBar() {
               >
                 {t('nav.auditLog')}
               </button>
+              <a
+                href="/docs"
+                target="_blank"
+                rel="noopener noreferrer"
+                onClick={() => setUserMenuOpen(false)}
+                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"
+              >
+                <Code className="w-4 h-4" aria-hidden="true" strokeWidth={2} />
+                {t('settings.apiDocs', 'API Dokumentation')}
+              </a>
               <button
                 onClick={handleLogout}
                 className="w-full text-left px-3 py-2 text-sm text-danger-600 hover:bg-danger-50 min-h-touch focus:outline-none focus-visible:ring-2 focus-visible:ring-danger-500"