feat: sprint 1 — auth + CRUD engagements

Ship the first feature end-to-end on the UI: users log in with JWT,
admins manage user accounts, and any authenticated user (per RBAC)
can create, list, view, edit, and delete engagements.

Backend (Flask + SQLAlchemy + SQLite, 63 pytest)
- User / Engagement models, Alembic 0001 initial schema
- argon2 password hashing, JWT bearer (60-min TTL), @login_required
  and @role_required decorators
- 13 API endpoints under /api/*, including last-admin protection on
  DELETE/PATCH user and JSON 404 on unknown /api/* paths
- `flask create-admin` CLI with duplicate / short-password handling

Frontend (React + Vite + Tailwind + TanStack Query, 20 vitest)
- Inter font bundled locally (no CDN), DESIGN.md tokens in Tailwind
- LoginPage / EngagementsList / EngagementForm / EngagementDetail /
  UsersAdmin pages with role-aware UI
- Layout, ProtectedRoute, StatusBadge, FormField, LoadingState,
  ErrorState, EmptyState, Toast + provider
- Axios client: Bearer interceptor, 401 → purge + /login + "Session
  expirée" toast, 403 → "Accès refusé" toast (declarative <Navigate>
  for already-authed users, Fragment-keyed admin user rows)

Deployment
- Single multistage Dockerfile (node:20-alpine → python:3.12-slim)
- docker/entrypoint.sh runs `flask db upgrade` before `flask run`
- Makefile: build/start/stop/restart/update/logs/create-admin/
  update-mitre/test-{backend,frontend,e2e}/clean
- .env.example documenting MIMIC_JWT_SECRET / MIMIC_DB_PATH / MIMIC_PORT
- SQLite at /data/mimic.sqlite on named volume mimic-data

Acceptance suite (Playwright, 36 tests, all 27 ACs)
- e2e/ scaffold with playwright.config + auth/api fixtures
- One spec per user story (us1-bootstrap through us6-deployment)
- Portable via MIMIC_CONTAINER_CMD / MIMIC_BASE_URL (docker or podman)

Docs
- README.md with quick-start and architecture overview
- CHANGELOG.md updated with Sprint 1 deliverables
- pyrightconfig.json so the Python LSP sees backend/.venv and
  resolves the `backend.app.*` absolute imports

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/tests/apiClient.test.tsx

@@ -0,0 +1,57 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import MockAdapter from 'axios-mock-adapter';
+import { apiClient, getToken, registerUnauthorizedHandler, setToken } from '@/api/client';
+
+describe('apiClient interceptors', () => {
+  let mock: MockAdapter;
+
+  beforeEach(() => {
+    mock = new MockAdapter(apiClient);
+    setToken(null);
+  });
+
+  afterEach(() => {
+    mock.restore();
+    setToken(null);
+  });
+
+  it('attaches Bearer token from storage', async () => {
+    setToken('abc123');
+    mock.onGet('/auth/me').reply((config) => {
+      expect(config.headers?.Authorization).toBe('Bearer abc123');
+      return [200, { id: 1, username: 'alice', role: 'admin', created_at: '2026-01-01' }];
+    });
+
+    const resp = await apiClient.get('/auth/me');
+    expect(resp.status).toBe(200);
+  });
+
+  it('purges token and calls the registered handler on 401', async () => {
+    setToken('expired');
+    const handler = vi.fn();
+    registerUnauthorizedHandler(handler);
+
+    mock.onGet('/engagements').reply(401, { error: 'token expired' });
+
+    await expect(apiClient.get('/engagements')).rejects.toMatchObject({
+      response: { status: 401 },
+    });
+
+    expect(getToken()).toBeNull();
+    expect(handler).toHaveBeenCalledTimes(1);
+
+    // Reset to avoid leaking into other tests.
+    registerUnauthorizedHandler(() => {});
+  });
+
+  it('leaves the token intact on non-401 errors', async () => {
+    setToken('still-valid');
+    mock.onGet('/users').reply(403, { error: 'forbidden' });
+
+    await expect(apiClient.get('/users')).rejects.toMatchObject({
+      response: { status: 403 },
+    });
+
+    expect(getToken()).toBe('still-valid');
+  });
+});