Fix typo

[thedorCode-star]

1. tests:
   Redirects to login when clicking "Sign out"
   Shows login form with cleared fields after logout
   Allows logging in again after logout

2. Registration flow
   Server (server.js)
   In-memory user store with testuser and locked preloaded
   POST /register with validation (required fields, password length ≥ 6, duplicate username)
   Login now uses the user store (supports newly registered users)
   Registration page (public/register.html)
   Username, email, password, confirm password
   Client-side validation (passwords match, min 6 chars)
   Link to login page
   Registration tests (tests/registration.spec.js)
   7 tests:
   Form displays all required fields
   Valid registration redirects to login
   New user can log in after registration
   Duplicate username shows error
   Mismatched passwords show error
   Short password shows error
   Link to login page exists and works

3. Other changes
   Added Register link on login page
   Updated README with logout and registration sections