Refactor: Codebase restructuring, added unit tests, CI workflow

[quinneden]

This pull request introduces significant updates to the acmsg project, focusing on improving automation, restructuring the codebase, enhancing dependency management, and refining the CLI functionality. Key changes include the addition of a GitHub Actions workflow for testing, restructuring of the source code, and updates to project configuration files.

CI/CD and Testing Enhancements:

• Added a GitHub Actions workflow (.github/workflows/test.yaml) to automate testing, type checking, and code coverage reporting for the main branch. This includes steps for setting up Python, syncing dependencies, running tests with pytest, and uploading coverage reports to Codecov.
• Introduced a pytest.ini configuration file to standardize test discovery and coverage reporting.

Codebase Restructuring:

• Refactored the src/acmsg package to modularize functionality, including the addition of __init__.py files for better package management and re-exports of key components. [1] [2]
• Simplified the CLI entry point (src/acmsg/__main__.py) by delegating command handling to dedicated modules and removing redundant code for improved maintainability.

Dependency and Build Management:

• Updated pyproject.toml to include type stubs for dependencies (types-colorama, types-pyyaml, types-requests) and restructured package discovery using tool.setuptools.packages.find. [1] [2]
• Added a justfile with common project tasks such as build, test, sync, and bump-version to streamline development workflows.

Asset and File Management:

• Updated MANIFEST.in to include Python files and moved asset paths from src/acmsg/assets to src/acmsg/templates/assets.

Documentation and Cleanup:

• Removed outdated TODO items from TODO.md to reflect the current state of the project.