feat(M4): System-Rueckbau — Dashboard-Inhalte als MiniApps, Core = reiner Host (#362)

- system_miniapps.py: audit_activity (audit:read, settings max_items) + system_metrics (settings:read) als Core-Apps in Registry
- base.py-Fix: native Manifest-MiniApps reichen component durch (M1-Luecke)
- contacts-Manifest: contacts_stats (ContactsStatsWidget, contacts:read, show_companies/show_persons)
- Seed-Fix: nur renderbare Apps (component) landen im Dashboard-Layout
- Frontend: ContactsStatsWidget, AuditActivityWidget, SystemMetricsWidget; MiniAppHost-Registry +3
- Dashboard.tsx = reiner Host (26 Z.); Page-Tests auf Pure-Host umgeschrieben
- Tests: M4 7/7 (TDD rot->gruen), Backend-Regression 46/46, Vitest 22/22, tsc clean, build OK

frontend/src/__tests__/dashboard/Dashboard.test.tsx

@@ -5,48 +5,21 @@ import { MemoryRouter } from 'react-router-dom';
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
 import { DashboardPage } from '@/pages/Dashboard';
 
-vi.mock('@/api/hooks', () => ({
-  useUnifiedContacts: (page: number, pageSize: number, search: any, type: string) => ({
-    data: { items: [], total: type === 'company' ? 24 : 156, page: 1, page_size: 25 },
-    isLoading: false,
-  }),
-  useAuditLog: () => ({
-    data: {
-      items: [
-        { timestamp: '2025-06-29T10:00:00Z', user: 'anna.schmidt', action: 'create', entity: 'company', entity_id: '1', details: 'Firma erstellt' },
-        { timestamp: '2025-06-28T14:00:00Z', user: 'max.mustermann', action: 'update', entity: 'contact', entity_id: '2', details: 'Kontakt aktualisiert' },
-        { timestamp: '2025-06-27T09:00:00Z', user: 'admin', action: 'delete', entity: 'company', entity_id: '3', details: 'Firma gelöscht' },
-      ],
-      total: 3,
-    },
-    isError: false,
-  }),
+/**
+ * DashboardPage tests (Phase M4): the page is a pure host — all content
+ * (stat cards, activity feed, system metrics) lives in MiniApp instances
+ * managed by the DashboardBuilder. The former legacy assertions
+ * (stat-companies etc.) moved to the widget level in M4.
+ */
+
+vi.mock('react-i18next', () => ({
+  useTranslation: () => ({ t: (key: string) => key }),
 }));
 
-vi.mock('@/api/dashboard', () => ({
-  useDashboardWidgets: () => ({
-    data: { items: [], total: 0 },
-    isError: false,
-  }),
-}));
-
-// M3: DashboardPage renders the DashboardBuilder — mock its data layer
-vi.mock('@/api/dashboards', () => ({
-  useDashboards: () => ({ data: [], isLoading: false }),
-  useCreateDashboard: () => ({ mutate: vi.fn(), isPending: false }),
-  useUpdateDashboard: () => ({ mutate: vi.fn(), isPending: false }),
-  useDeleteDashboard: () => ({ mutate: vi.fn() }),
-  useSetDefaultDashboard: () => ({ mutate: vi.fn() }),
-}));
-
-vi.mock('@/api/miniapps', () => ({
-  useMiniapps: () => ({ data: { items: [], total: 0 } }),
-  renderableDashboardApps: (apps: unknown[]) => (apps as never[]),
-}));
-
-vi.mock('@/components/dashboard/MiniAppHost', () => ({
-  MiniAppHost: ({ appId }: { appId: string }) => (
-    <div data-testid={`miniapp-${appId}`}>app:{appId}</div>
+// DashboardBuilder is covered by its own suite — render a stub here
+vi.mock('@/components/dashboard/DashboardBuilder', () => ({
+  DashboardBuilder: () => (
+    <div data-testid="dashboard-builder-stub">builder</div>
   ),
 }));
 
@@ -64,64 +37,27 @@ function renderPage() {
   );
 }
 
-describe('DashboardPage', () => {
-  it('renders dashboard page', () => {
+describe('DashboardPage (pure host, M4)', () => {
+  it('renders the dashboard page shell', () => {
     renderPage();
     expect(screen.getByTestId('dashboard-page')).toBeInTheDocument();
   });
 
-  it('renders page title', () => {
+  it('renders the page title', () => {
     renderPage();
-    expect(screen.getByText('Dashboard')).toBeInTheDocument();
+    expect(screen.getByText('dashboard.title')).toBeInTheDocument();
   });
 
-  it('renders stat card for companies', () => {
+  it('renders the DashboardBuilder as its only content area', () => {
     renderPage();
-    expect(screen.getByTestId('stat-companies')).toBeInTheDocument();
+    expect(screen.getByTestId('dashboard-builder-stub')).toBeInTheDocument();
   });
 
-  it('renders stat card for contacts', () => {
+  it('does not render legacy hard-coded blocks anymore', () => {
     renderPage();
-    expect(screen.getByTestId('stat-contacts')).toBeInTheDocument();
-  });
-
-  it('renders stat card for active this week', () => {
-    renderPage();
-    expect(screen.getByTestId('stat-active-week')).toBeInTheDocument();
-  });
-
-  it('renders stat card for new this month', () => {
-    renderPage();
-    expect(screen.getByTestId('stat-new-month')).toBeInTheDocument();
-  });
-
-  it('renders correct company count in stat card', () => {
-    renderPage();
-    const statCompanies = screen.getByTestId('stat-companies');
-    expect(statCompanies).toHaveTextContent('24');
-  });
-
-  it('renders correct contact count in stat card', () => {
-    renderPage();
-    const statContacts = screen.getByTestId('stat-contacts');
-    expect(statContacts).toHaveTextContent('156');
-  });
-
-  it('renders activity feed', () => {
-    renderPage();
-    expect(screen.getByTestId('activity-feed')).toBeInTheDocument();
-  });
-
-  it('renders activity feed with user names from audit log', () => {
-    renderPage();
-    expect(screen.getByText('anna.schmidt')).toBeInTheDocument();
-    expect(screen.getByText('max.mustermann')).toBeInTheDocument();
-  });
-
-  it('renders activity feed with action descriptions', () => {
-    renderPage();
-    expect(screen.getByText(/create/)).toBeInTheDocument();
-    expect(screen.getByText(/update/)).toBeInTheDocument();
-    expect(screen.getByText(/delete/)).toBeInTheDocument();
+    expect(screen.queryByTestId('stat-companies')).not.toBeInTheDocument();
+    expect(screen.queryByTestId('stat-contacts')).not.toBeInTheDocument();
+    expect(screen.queryByTestId('stat-active-week')).not.toBeInTheDocument();
+    expect(screen.queryByTestId('activity-feed')).not.toBeInTheDocument();
   });
 });