PR: Add Login and Protected ResumeBook Route

[nicoleluo7]

Summary

This PR implements a basic authentication flow for the website. It introduces a login page with hardcoded credentials and protects the /resume-book route so only authenticated users can access it.

Changes Made

1. Login Page (Login.jsx and Login.css)

• Added login form with username and password fields
• Currently, there are hardcoded credentials for username and password for demonstration purposes.
• Error message is displayed for invalid credentials

2. PrivateRoute Component (PrivateRoute.jsx)

• Wraps protected routes
• Checks for authentication, redirects unauthenticated users to /login

3. App Routing (App.js)

• Added /login route
• Wrapped /resume-book with PrivateRoute to require authentication

Testing

1. Navigate to /resume-book directly; you should be redirected to /login.
2. Log in with "username" and "password".
3. On successful login, you should be redirected to /resume-book.
4. Invalid credentials should show an error message

Notes

• This is currently a simple, client-side authentication for demonstration only.
• Credentials and authentication logic should be replaced with a secure backend in the future