feat(frontend): c2 config card + execute modal (sprint 8 phase 1)

- frontend/src/api/c2.ts: 6 typed API calls (getC2Config, putC2Config,
  deleteC2Config, testC2Config, listCallbacks, executeC2) following the
  frozen M1+M2 backend contracts
- frontend/src/api/types.ts: C2Config, C2ConfigInput, C2TestResult,
  C2Callback, C2CallbacksResponse, C2Task, C2ExecuteInput, C2ExecuteResponse
- frontend/src/hooks/useC2.ts: useC2Config, useUpdateC2Config,
  useDeleteC2Config, useTestC2Config, useC2Callbacks, useExecuteC2
- frontend/src/components/C2ConfigCard.tsx: engagement-scoped C2 config
  card (url + write-only token + verify-tls + save/delete/test-connection),
  503 disabled state, ConfirmDialog on delete
- frontend/src/components/ExecuteViaC2Modal.tsx: callback picker table
  (mono data cells), commands textarea pre-filled from rt.commands,
  Launch disabled until row selected + non-empty commands
- frontend/src/pages/EngagementFormPage.tsx: embed C2ConfigCard in edit
  mode only, admin+redteam only (canEditEngagements gate)
- frontend/src/pages/SimulationFormPage.tsx: Execute via C2 button in RT
  card, visible only when !isDone && canEditRT && hasC2Config; opens modal
- Tests: 33 new tests across api/c2, components/C2ConfigCard,
  components/ExecuteViaC2Modal, EngagementFormPage, SimulationFormPage
  (172 total, 139 baseline + 33 new, all passing)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/tests/components/ExecuteViaC2Modal.test.tsx

@@ -0,0 +1,160 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { screen, waitFor, fireEvent } from '@testing-library/react';
+import MockAdapter from 'axios-mock-adapter';
+import { apiClient } from '@/api/client';
+import { ExecuteViaC2Modal } from '@/components/ExecuteViaC2Modal';
+import { renderWithProviders } from '../utils';
+
+vi.mock('@/hooks/useAuth', () => ({
+  useAuth: () => ({
+    user: { id: 1, username: 'alice', role: 'redteam', created_at: '2026-01-01' },
+    status: 'authenticated',
+    login: vi.fn(),
+    logout: vi.fn(),
+    isAdmin: false,
+    isRedteam: true,
+    isSoc: false,
+    canEditEngagements: true,
+  }),
+}));
+
+const CALLBACKS = [
+  {
+    display_id: 1,
+    active: true,
+    host: 'WIN-TARGET',
+    user: 'administrator',
+    domain: 'lab.local',
+    last_checkin: '2026-06-10T10:00:00',
+  },
+  {
+    display_id: 2,
+    active: false,
+    host: 'WIN-DC01',
+    user: 'SYSTEM',
+    domain: 'lab.local',
+    last_checkin: '2026-06-10T09:00:00',
+  },
+];
+
+let mock: MockAdapter;
+
+beforeEach(() => {
+  mock = new MockAdapter(apiClient);
+  mock.onGet('/engagements/42/c2/callbacks').reply(200, { callbacks: CALLBACKS });
+});
+
+afterEach(() => {
+  mock.restore();
+  vi.clearAllMocks();
+});
+
+function renderModal(initialCommands = 'whoami\nipconfig') {
+  const onClose = vi.fn();
+  renderWithProviders(
+    <ExecuteViaC2Modal
+      simulationId={7}
+      engagementId={42}
+      initialCommands={initialCommands}
+      onClose={onClose}
+    />,
+  );
+  return { onClose };
+}
+
+describe('ExecuteViaC2Modal', () => {
+  it('renders modal with title and callback table', async () => {
+    renderModal();
+    expect(screen.getByTestId('c2-modal')).toBeInTheDocument();
+    expect(screen.getByText('Execute via C2')).toBeInTheDocument();
+    await waitFor(() => {
+      expect(screen.getAllByTestId('c2-callback-row')).toHaveLength(2);
+    });
+  });
+
+  it('renders callback rows with mono data', async () => {
+    renderModal();
+    await waitFor(() => {
+      expect(screen.getByText('WIN-TARGET')).toBeInTheDocument();
+      expect(screen.getByText('WIN-DC01')).toBeInTheDocument();
+      expect(screen.getByText('administrator')).toBeInTheDocument();
+    });
+  });
+
+  it('Launch button is disabled before selecting a callback', async () => {
+    renderModal();
+    await waitFor(() => {
+      expect(screen.getAllByTestId('c2-callback-row')).toHaveLength(2);
+    });
+    expect(screen.getByTestId('c2-launch-btn')).toBeDisabled();
+  });
+
+  it('Launch button is disabled when commands are empty', async () => {
+    renderModal('');
+    await waitFor(() => {
+      expect(screen.getAllByTestId('c2-callback-row')).toHaveLength(2);
+    });
+    fireEvent.click(screen.getAllByTestId('c2-callback-row')[0]);
+    expect(screen.getByTestId('c2-launch-btn')).toBeDisabled();
+  });
+
+  it('Launch button enabled after selecting row and having commands', async () => {
+    renderModal('whoami');
+    await waitFor(() => {
+      expect(screen.getAllByTestId('c2-callback-row')).toHaveLength(2);
+    });
+    fireEvent.click(screen.getAllByTestId('c2-callback-row')[0]);
+    expect(screen.getByTestId('c2-launch-btn')).not.toBeDisabled();
+  });
+
+  it('calls executeC2 with correct body and closes modal on success', async () => {
+    mock.onPost('/simulations/7/c2/execute').reply(200, {
+      tasks: [
+        { id: 1, mythic_task_display_id: 10, command: 'whoami', status: 'submitted', completed: false },
+        { id: 2, mythic_task_display_id: 11, command: 'ipconfig', status: 'submitted', completed: false },
+      ],
+    });
+    const { onClose } = renderModal('whoami\nipconfig');
+    await waitFor(() => {
+      expect(screen.getAllByTestId('c2-callback-row')).toHaveLength(2);
+    });
+    fireEvent.click(screen.getAllByTestId('c2-callback-row')[0]);
+    fireEvent.click(screen.getByTestId('c2-launch-btn'));
+    await waitFor(() => {
+      expect(onClose).toHaveBeenCalled();
+    });
+    const req = mock.history['post'][0];
+    const body = JSON.parse(req.data as string);
+    expect(body.callback_display_id).toBe(1);
+    expect(body.commands).toEqual(['whoami', 'ipconfig']);
+  });
+
+  it('shows inline error and keeps modal open on executeC2 failure', async () => {
+    mock.onPost('/simulations/7/c2/execute').reply(500, { error: 'Mythic unreachable' });
+    const { onClose } = renderModal('whoami');
+    await waitFor(() => {
+      expect(screen.getAllByTestId('c2-callback-row')).toHaveLength(2);
+    });
+    fireEvent.click(screen.getAllByTestId('c2-callback-row')[0]);
+    fireEvent.click(screen.getByTestId('c2-launch-btn'));
+    await waitFor(() => {
+      expect(screen.getByText('Mythic unreachable')).toBeInTheDocument();
+    });
+    expect(onClose).not.toHaveBeenCalled();
+  });
+
+  it('Cancel button calls onClose', async () => {
+    const { onClose } = renderModal();
+    await waitFor(() => {
+      expect(screen.getAllByTestId('c2-callback-row')).toHaveLength(2);
+    });
+    fireEvent.click(screen.getByRole('button', { name: /cancel/i }));
+    expect(onClose).toHaveBeenCalled();
+  });
+
+  it('prefills commands textarea from initialCommands', async () => {
+    renderModal('net user\nwhoami /all');
+    const textarea = screen.getByTestId('c2-commands-textarea') as HTMLTextAreaElement;
+    expect(textarea.value).toBe('net user\nwhoami /all');
+  });
+});