feat(ui): External-Agent-API + Besitzübertragung UI (UI-Backlog Module 15+16/16)

Modul 15 External-Agent (ai_assistant-Plugin, Manifest settings_page):
- SettingsExternalAgents.tsx: Agentenliste mit curl-Snippets (run/status/stream),
  Copy-Buttons, Bearer-Token-Hinweis, Rate-Limit-Doku, Token-Link
- api/externalAgent.ts (useAiAgents, buildCurlSnippets, curlCommand)
- Manifest: settings_pages +external-agents (order 61, permission ai:read)
- Komponenten-Map regeneriert (43)

Modul 16 Ownership-Transfer (Core):
- SettingsOwnership.tsx: Admin-Gate, From/To-User-Selects, 10 Entity-Type-Chips,
  ConfirmDialog, Ergebnis-Tabelle
- api/ownership.ts (useTransferOwnership, OWNERSHIP_ENTITY_TYPES)
- Route /settings/ownership + Nav-Eintrag

i18n de/en +28 Keys. Vitest 12/12, tsc 0, Build OK, ruff OK, Manifest-Import OK

frontend/src/__tests__/pages/SettingsExternalAgents.test.tsx

@@ -0,0 +1,102 @@
+/**
+ * External Agents settings page tests — integration guide UI
+ * (UI-Backlog module 15/16).
+ *
+ * Covers: page render, agent cards with curl snippets, copy buttons,
+ * empty state, auth hint with token link.
+ */
+import React from 'react';
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { MemoryRouter } from 'react-router-dom';
+import { SettingsExternalAgentsPage } from '@/pages/SettingsExternalAgents';
+
+type AgentLike = {
+  id: string;
+  name: string;
+  description: string;
+  is_active: boolean;
+};
+
+const makeAgent = (overrides: Partial<AgentLike> = {}): AgentLike => ({
+  id: '11111111-1111-1111-1111-111111111111',
+  name: 'Helpdesk Agent',
+  description: 'Answers support questions',
+  is_active: true,
+  ...overrides,
+});
+
+let mockAgents: AgentLike[] = [];
+let mockLoading = false;
+
+vi.mock('@/api/externalAgent', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('@/api/externalAgent')>();
+  return {
+    ...actual,
+    useAiAgents: () => ({ data: mockAgents, isLoading: mockLoading, isError: false }),
+  };
+});
+
+function renderPage() {
+  return render(
+    <MemoryRouter>
+      <SettingsExternalAgentsPage />
+    </MemoryRouter>,
+  );
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  mockAgents = [];
+  mockLoading = false;
+});
+
+describe('SettingsExternalAgentsPage', () => {
+  it('renders the page with auth hint and token link', () => {
+    renderPage();
+    expect(screen.getByTestId('settings-external-agents-page')).toBeInTheDocument();
+    expect(screen.getByRole('link', { name: /API-Tokens verwalten|Manage API tokens/i })).toBeInTheDocument();
+  });
+
+  it('renders empty state when no agents exist', () => {
+    renderPage();
+    expect(screen.getByText(/Keine KI-Agenten|No AI agents/i)).toBeInTheDocument();
+  });
+
+  it('renders agent cards with three curl snippets each', () => {
+    mockAgents = [makeAgent()];
+    renderPage();
+    expect(screen.getByTestId('external-agent-card-11111111-1111-1111-1111-111111111111')).toBeInTheDocument();
+    expect(screen.getByTestId('curl-snippet-11111111-1111-1111-1111-111111111111-runAgent')).toBeInTheDocument();
+    expect(screen.getByTestId('curl-snippet-11111111-1111-1111-1111-111111111111-getStatus')).toBeInTheDocument();
+    expect(screen.getByTestId('curl-snippet-11111111-1111-1111-1111-111111111111-streamAgent (SSE)')).toBeInTheDocument();
+  });
+
+  it('curl snippets contain endpoint URLs and bearer placeholder', () => {
+    mockAgents = [makeAgent()];
+    renderPage();
+    const runSnippet = screen.getByTestId('curl-snippet-11111111-1111-1111-1111-111111111111-runAgent');
+    expect(runSnippet.textContent).toContain('/api/v1/external/agent/11111111-1111-1111-1111-111111111111/run');
+    expect(runSnippet.textContent).toContain('Bearer <API_TOKEN>');
+    const statusSnippet = screen.getByTestId('curl-snippet-11111111-1111-1111-1111-111111111111-getStatus');
+    expect(statusSnippet.textContent).toContain('/status');
+  });
+
+  it('renders copy buttons per snippet', () => {
+    mockAgents = [makeAgent()];
+    renderPage();
+    expect(screen.getByTestId('curl-copy-11111111-1111-1111-1111-111111111111-runAgent')).toBeInTheDocument();
+    expect(screen.getByTestId('curl-copy-11111111-1111-1111-1111-111111111111-getStatus')).toBeInTheDocument();
+  });
+
+  it('renders multiple agents', () => {
+    mockAgents = [
+      makeAgent(),
+      makeAgent({ id: '22222222-2222-2222-2222-222222222222', name: 'Second Agent', is_active: false }),
+    ];
+    renderPage();
+    expect(screen.getByTestId('external-agent-card-11111111-1111-1111-1111-111111111111')).toBeInTheDocument();
+    expect(screen.getByTestId('external-agent-card-22222222-2222-2222-2222-222222222222')).toBeInTheDocument();
+    expect(screen.getByText('Second Agent')).toBeInTheDocument();
+  });
+});

frontend/src/__tests__/pages/SettingsOwnership.test.tsx

@@ -0,0 +1,146 @@
+/**
+ * Ownership transfer settings page tests — admin bulk ownership transfer
+ * (UI-Backlog module 16/16).
+ *
+ * Covers: admin gate, user selects, entity type toggles, submit gating,
+ * transfer flow with result display.
+ */
+import React from 'react';
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { MemoryRouter } from 'react-router-dom';
+import { SettingsOwnershipPage } from '@/pages/SettingsOwnership';
+
+const transferMut = vi.fn().mockResolvedValue({
+  message: 'Ownership transfer completed',
+  results: { contacts: 5, workflows: 0 },
+});
+
+const makeUser = (id: string, name: string, email: string) => ({
+  id,
+  email,
+  name,
+  first_name: null,
+  last_name: null,
+  avatar_url: null,
+  role: 'admin',
+  role_id: null,
+  is_active: true,
+  tenant_id: 't-1',
+});
+
+let mockIsAdmin = true;
+let mockUsers: unknown[] = [];
+let mockLoading = false;
+
+vi.mock('@/api/ownership', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('@/api/ownership')>();
+  return {
+    ...actual,
+    useTransferOwnership: () => ({ mutate: transferMut, mutateAsync: transferMut, isPending: false }),
+  };
+});
+
+vi.mock('@/api/users', () => ({
+  useUsers: () => ({ data: { items: mockUsers, total: mockUsers.length }, isLoading: mockLoading }),
+}));
+
+vi.mock('@/store/authStore', () => ({
+  useAuthStore: (selector: (state: { user: { is_system_admin: boolean } | null }) => unknown) =>
+    selector({ user: { is_system_admin: mockIsAdmin } }),
+}));
+
+function renderPage() {
+  return render(
+    <MemoryRouter>
+      <SettingsOwnershipPage />
+    </MemoryRouter>,
+  );
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  mockIsAdmin = true;
+  mockLoading = false;
+  mockUsers = [
+    makeUser('11111111-1111-1111-1111-111111111111', 'Alte Mitarbeiterin', 'old@example.de'),
+    makeUser('22222222-2222-2222-2222-222222222222', 'Nachfolger', 'new@example.de'),
+  ];
+  transferMut.mockResolvedValue({
+    message: 'Ownership transfer completed',
+    results: { contacts: 5, workflows: 0 },
+  });
+});
+
+describe('SettingsOwnershipPage', () => {
+  it('renders admin-only notice for non-admin users', () => {
+    mockIsAdmin = false;
+    renderPage();
+    expect(screen.getByTestId('ownership-admin-only')).toBeInTheDocument();
+    expect(screen.queryByTestId('ownership-form')).not.toBeInTheDocument();
+  });
+
+  it('renders the form with two user selects and 10 entity type buttons', () => {
+    renderPage();
+    expect(screen.getByTestId('ownership-form')).toBeInTheDocument();
+    expect(screen.getByTestId('ownership-from')).toBeInTheDocument();
+    expect(screen.getByTestId('ownership-to')).toBeInTheDocument();
+    expect(screen.getByTestId('ownership-type-contacts')).toBeInTheDocument();
+    expect(screen.getByTestId('ownership-type-notifications')).toBeInTheDocument();
+  });
+
+  it('submit is disabled without both users selected', () => {
+    renderPage();
+    const btn = screen.getByTestId('ownership-submit-btn') as HTMLButtonElement;
+    expect(btn.disabled).toBe(true);
+  });
+
+  it('submit is disabled when from and to are the same user', () => {
+    renderPage();
+    const from = screen.getByTestId('ownership-from') as HTMLSelectElement;
+    fireEvent.change(from, { target: { value: '11111111-1111-1111-1111-111111111111' } });
+    const to = screen.getByTestId('ownership-to') as HTMLSelectElement;
+    fireEvent.change(to, { target: { value: '11111111-1111-1111-1111-111111111111' } });
+    const btn = screen.getByTestId('ownership-submit-btn') as HTMLButtonElement;
+    expect(btn.disabled).toBe(true);
+  });
+
+  it('toggles entity types on click', () => {
+    renderPage();
+    const chip = screen.getByTestId('ownership-type-contacts');
+    expect(chip.getAttribute('aria-pressed')).toBe('false');
+    fireEvent.click(chip);
+    expect(chip.getAttribute('aria-pressed')).toBe('true');
+    fireEvent.click(chip);
+    expect(chip.getAttribute('aria-pressed')).toBe('false');
+  });
+
+  it('transfers ownership after confirmation and shows the result', async () => {
+    renderPage();
+    const from = screen.getByTestId('ownership-from') as HTMLSelectElement;
+    fireEvent.change(from, { target: { value: '11111111-1111-1111-1111-111111111111' } });
+    const to = screen.getByTestId('ownership-to') as HTMLSelectElement;
+    fireEvent.change(to, { target: { value: '22222222-2222-2222-2222-222222222222' } });
+    fireEvent.click(screen.getByTestId('ownership-type-contacts'));
+
+    const btn = screen.getByTestId('ownership-submit-btn') as HTMLButtonElement;
+    expect(btn.disabled).toBe(false);
+    fireEvent.click(btn);
+
+    const confirmBtn = await screen.findByRole('button', { name: 'Bestätigen' });
+    fireEvent.click(confirmBtn);
+
+    await waitFor(() => {
+      expect(transferMut).toHaveBeenCalledTimes(1);
+    });
+    expect(transferMut).toHaveBeenCalledWith({
+      from_user_id: '11111111-1111-1111-1111-111111111111',
+      to_user_id: '22222222-2222-2222-2222-222222222222',
+      entity_types: ['contacts'],
+    });
+
+    await waitFor(() => {
+      expect(screen.getByTestId('ownership-result')).toBeInTheDocument();
+    });
+  });
+});