Add test suite and CI configuration

[jensens]

Summary

Add comprehensive testing infrastructure and GitHub Actions CI workflow.

Changes

Testing Infrastructure:

• Created comprehensive test suite with 30+ test cases
• Tests cover all major functions: utility functions, GitHub API integration, and all perform_* commands
• Includes pytest fixtures for mocking subprocess calls, git repositories, and API responses
• Achieves ~80% code coverage
• Tests use proper mocking to avoid external dependencies

CI/CD:

• GitHub Actions workflow testing on Python 3.9, 3.10, 3.11, 3.12, 3.13, and 3.14
• Runs on push to main and all pull requests
• Executes ruff linting, isort checking, and pytest with coverage
• Optional Codecov integration for coverage reporting

Code Quality Configuration:

• Configured ruff with essential rules: E (pycodestyle), F (pyflakes), B (bugbear), UP (pyupgrade), S (bandit security)
• Added pytest configuration in pyproject.toml
• Updated test dependencies: pytest, pytest-cov, pytest-mock
• Kept isort separate from ruff (uses force_alphabetical_sort which ruff doesn't support)

Housekeeping:

• Updated .gitignore to exclude local config files

Test Coverage

The test suite covers:

• Utility functions (listdir, hilite, get_branch)
• GitHub API integration (query_repos with org/user fallback, pagination)
• All perform_* functions (clone, pull, status, branch, diff, commit, push, checkout, backup)
• Edge cases (non-git directories, files vs directories, specific vs all repos)

[jensens]

CI Failures

The GitHub Actions CI is failing because ruff is catching code quality and security issues in the existing code:

Issues found:

• UP031: Old-style percent formatting (should use f-strings or .format())
• S310: Audit URL open for permitted schemes
• S602: subprocess call with shell=True (security issue)
• S603: subprocess call - check for execution of untrusted input

Will fix the code to pass ruff checks.

[jensens]

Makefile enhancements

• mxmake update ro get latest mxmake improvements
• uvx mxmake and enabled tests, edit mx.ini to configure tests