This pull request updates the authentication logic in app.py to securely store and verify passwords using hashing. It replaces plain text password storage and comparison with hashed passwords for both students and teachers, improving the application's security. Additionally, it makes a minor change to how the database path is defined.

Security improvements:

• Passwords are now hashed before being stored in the database for both students and teachers during registration using generate_password_hash. [1] [2]
• Password verification during login now uses check_password_hash to compare the entered password with the stored hashed password for both students and teachers. [1] [2]
• The necessary imports for password hashing and checking (generate_password_hash, check_password_hash from werkzeug.security) have been added.

Codebase consistency:

• The database path definition now uses an absolute path for consistency and reliability.This PR introduces secure password storage using Werkzeug's generate_password_hash and check_password_hash. Passwords are no longer stored in plaintext. Existing passwords in ams.db have been migrated.

solves #19