Add password authentication and encryption

### Add Password Authentication & Encryption

#### Proposed Solution
1. **Add password authentication** for all user login and registration actions.
2. **Encrypt passwords** before storing them in the csv using a secure algorithm (e.g., **SHA-256**, **bcrypt**, or **argon2**).
3. **Verify passwords** during login by comparing the hashed version of the entered password with the stored hash.
4. (Optional) Implement **password strength validation** and **password reset functionality**. (100-200 extra bounty points)

#### Acceptance Criteria
- [ ] Users can register with a password that is securely hashed.
- [ ] Login authentication validates passwords securely.
- [ ] No plain text passwords are stored in the csv file.
- [ ] Unit tests verify encryption and authentication functionality