test: increase test coverage

[ImBIOS]

This PR adds unit tests to increase test coverage for the BYOB project, focusing on core functionality and modules.

Changes

• Added tests for the security module (AES encryption/decryption, CBC mode, and Diffie-Hellman key exchange)
• Added tests for the portscanner module with proper mocking to avoid actual network connections
• Added a Makefile to simplify running tests and generating coverage reports
• Added requirements-dev.txt for development dependencies

Benefits

• Ensures critical security components work as expected
• Validates module functionality without requiring actual network connections
• Sets up a foundation for more comprehensive testing coverage
• Makes it easier for contributors to run tests and keep code quality high

Testing

The tests can be run with:

# Install development dependencies
pip install -r requirements-dev.txt

# Run tests
make test

# Run tests with coverage
make coverage

Future Improvements

Additional test coverage could be added for:

• The web GUI
• Other modules like keylogger, persistence, etc.
• Client-server communication
• Integration tests for end-to-end functionality

This PR is a first step toward comprehensive test coverage for the entire project.