T07b: frontend feature pages — companies + contacts + settings + audit + dashboard + search

- 11 new feature pages (CompaniesList/Detail/Form, ContactsList/Detail/Form,
  SettingsProfile/Roles/Users, AuditLog, GlobalSearchResults)
- 3 page updates (Dashboard with StatCard+ActivityFeed, Settings with tree nav+Outlet,
  TopBar with SearchDropdown)
- 13 new routes in routes/index.tsx
- i18n updates (de.json + en.json) with companies/contacts/settings/audit/search keys
- 12 new test files + 2 existing test fixes (TopBar, AppShell)
- 7 shared components (DataGrid, Tabs, SearchDropdown, CsvImportDialog, StatCard,
  ActivityFeed, UnsavedChangesGuard)
- 16 new API hooks in hooks.ts
- Verification: 141 tests pass, build succeeds, tsc --noEmit clean

frontend/src/components/layout/TopBar.tsx

@@ -8,6 +8,7 @@ import { useTenant } from '@/hooks/useTenant';
 import { useLogout } from '@/api/hooks';
 import { Avatar } from '@/components/ui/Avatar';
 import { Badge } from '@/components/ui/Badge';
+import { SearchDropdown } from '@/components/shared/SearchDropdown';
 
 export function TopBar() {
   const { t } = useTranslation();
@@ -119,16 +120,8 @@ export function TopBar() {
         </div>
 
         {/* Search */}
-        <div className="hidden md:block relative">
-          <input
-            type="search"
-            placeholder={t('topbar.search')}
-            className="w-64 pl-10 pr-3 py-2 text-sm rounded-md border border-secondary-300 focus:outline-none focus:ring-2 focus:ring-primary-500 min-h-touch"
-            aria-label={t('topbar.search')}
-          />
-          <svg className="absolute left-3 top-1/2 -translate-y-1/2 w-4 h-4 text-secondary-400" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
-            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M21 21l-6-6m2-5a7 7 0 11-14 0 7 7 0 0114 0z" />
-          </svg>
+        <div className="hidden md:block">
+          <SearchDropdown placeholder={t('topbar.search')} />
         </div>
       </div>