feat: implement user registration and login authentication routes with JWT authentication

[Shreyanshi210205]

Description

This pull request adds JWT-based authentication to the auth routes , including secure password hashing with bcrypt. It includes the following functionality:
1.Added register route (POST /api/auth/register)
-Validates input
-Hashes user passwords with bcrypt
-Stores new users in MongoDB
4.Added login route (POST /api/auth/login)
-Verifies email and password
-Generates and returns a JWT token

Semver Changes

• Patch (bug fix, no new features)
• Minor (new features, no breaking changes)
• Major (breaking changes)

Issues

#2

Checklist

• I have read the Contributing Guidelines.

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