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__/contacts/ContactForm.test.tsx

@@ -0,0 +1,37 @@
+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 { ContactFormPage } from '@/pages/ContactForm';
+
+vi.mock('@/api/hooks', () => ({
+  useContact: () => ({ data: undefined, isLoading: false }),
+  useCreateContact: () => ({ mutateAsync: vi.fn(), isPending: false }),
+  useUpdateContact: () => ({ mutateAsync: vi.fn(), isPending: false }),
+  useCompanies: () => ({ data: { items: [{ id: '1', name: 'TestCorp GmbH' }], total: 1 }, isLoading: false }),
+}));
+
+vi.mock('@/components/ui/Toast', () => ({
+  useToast: () => ({ success: vi.fn(), error: vi.fn(), info: vi.fn() }),
+}));
+
+vi.mock('@/components/shared/UnsavedChangesGuard', () => ({
+  UnsavedChangesGuard: () => null,
+}));
+
+describe('ContactFormPage', () => {
+  it('renders form with first name field', () => {
+    render(<MemoryRouter><ContactFormPage /></MemoryRouter>);
+    expect(screen.getByLabelText(/Vorname/)).toBeInTheDocument();
+  });
+
+  it('renders form with last name field', () => {
+    render(<MemoryRouter><ContactFormPage /></MemoryRouter>);
+    expect(screen.getByLabelText(/Nachname/)).toBeInTheDocument();
+  });
+
+  it('renders email field', () => {
+    render(<MemoryRouter><ContactFormPage /></MemoryRouter>);
+    expect(screen.getByLabelText(/E-Mail/)).toBeInTheDocument();
+  });
+});