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/src/components/ProtectedRoute.tsx

@@ -0,0 +1,51 @@
+import { useEffect } from 'react';
+import { Navigate, Outlet, useLocation } from 'react-router-dom';
+import { useAuth } from '@/hooks/useAuth';
+import { useToast } from '@/hooks/useToast';
+import type { Role } from '@/api/types';
+import { LoadingState } from './LoadingState';
+
+interface ProtectedRouteProps {
+  /** Allowed roles. If omitted, any authenticated user passes. */
+  roles?: Role[];
+  /** Where to send users who lack the required role. */
+  redirectOnRoleDenied?: string;
+}
+
+/**
+ * Gate component: handles auth + role checks before rendering nested routes.
+ * - No token / no user → /login
+ * - Wrong role → redirect + "Accès refusé" toast (AC-3.7)
+ */
+export function ProtectedRoute({
+  roles,
+  redirectOnRoleDenied = '/engagements',
+}: ProtectedRouteProps): JSX.Element {
+  const { user, status } = useAuth();
+  const { push } = useToast();
+  const location = useLocation();
+
+  const roleDenied = Boolean(
+    status === 'authenticated' && user && roles && !roles.includes(user.role),
+  );
+
+  useEffect(() => {
+    if (roleDenied) {
+      push('Accès refusé', 'error');
+    }
+  }, [roleDenied, push]);
+
+  if (status === 'loading') {
+    return <LoadingState label="Loading session…" />;
+  }
+
+  if (status === 'unauthenticated' || !user) {
+    return <Navigate to="/login" replace state={{ from: location.pathname }} />;
+  }
+
+  if (roleDenied) {
+    return <Navigate to={redirectOnRoleDenied} replace />;
+  }
+
+  return <Outlet />;
+}