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/__tests__/dashboard/Dashboard.test.tsx

@@ -0,0 +1,32 @@
+import React from 'react';
+import { describe, it, expect, vi } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { MemoryRouter } from 'react-router-dom';
+import { DashboardPage } from '@/pages/Dashboard';
+
+vi.mock('@/api/hooks', () => ({
+  useCompanies: () => ({ data: { items: [], total: 24 }, isLoading: false }),
+  useContacts: () => ({ data: { items: [], total: 156 }, isLoading: false }),
+  useAuditLog: () => ({
+    data: {
+      items: [
+        { timestamp: '2025-06-29T10:00:00Z', user: 'anna.schmidt', action: 'create', entity: 'company', entity_id: '1', details: 'Firma erstellt' },
+      ],
+      total: 1,
+    },
+    isError: false,
+  }),
+}));
+
+describe('DashboardPage', () => {
+  it('renders dashboard page', () => {
+    render(<MemoryRouter><DashboardPage /></MemoryRouter>);
+    expect(screen.getByTestId('dashboard-page')).toBeInTheDocument();
+  });
+
+  it('renders stat cards', () => {
+    render(<MemoryRouter><DashboardPage /></MemoryRouter>);
+    expect(screen.getByTestId('stat-companies')).toBeInTheDocument();
+    expect(screen.getByTestId('stat-contacts')).toBeInTheDocument();
+  });
+});