✅ hooks/useAuth.ts — useAuth() hook with useState, useEffect, useCallback — In-memory token store with expiry tracking — Auto-refresh fires 5 minutes before expiry — Returns: { user, isLoggedIn, login, logout, error, isLoading } ✅ middleware/auth.ts — authenticateToken middleware — Discriminates TokenExpiredError vs JsonWebTokenError — Extends Express Request with req.user: AuthUser — Returns 401 with specific error codes per failure type ✅ routes/auth.ts — POST /auth/login with Zod validation — POST /auth/refresh with refresh token verification — Returns { accessToken, refreshToken, user } on success ✅ types/auth.ts — User, AuthState, LoginCredentials, JWTPayload interfaces — AuthResponse and AuthError types — LoginFormValues type for form binding