Backend Overview
Stack: Node.js, Express, TypeScript, Mongoose. Entry: backend/src/index.ts.
Layout: config/ (env, logger), db/ (Mongo connection), models/, routes/ (auth, users, admin, etc.), middleware/ (auth, CSRF, rate limit, etc.), utils/, scripts/, types/.
REST API; JSON; JWT in httpOnly cookies for auth; CSRF and CORS enforced.
Related: API overview, Environment and config