Fix: Login controller issue resolved & project cleanup

[kishan-semwal]

✨ What I’ve Done in This PR:

✅ Fixed the login functionality by correctly validating user credentials (email & password)
✅ Implemented missing utility methods in User model:

• setPassword
• isValidPassword
  ✅ Cleaned up the codebase by replacing broken code with the working version
  ✅ Structured the project with proper client/server separation
  ✅ Added proper .gitignore files to exclude:
• node_modules
• environment variables (.env)
• build artifacts
  ✅ Ensured admin login (testlibrarian@library.com) and member login work as expected
  ✅ Successfully tested all login scenarios using Postman

📌 This PR resolves the login issue and sets up the project for future enhancements with a clean and secure structure.