Python package setup (initial approach)

[bittner]

Adds an initial Python packaging setup.

• Renames the bin/ folder to src/ (to match the src layout recommended by Python packaging)
• Renames the LucasR.py module to main.py
• Adds a __name__ == "__main__"´ name guard to the main.py module (to allow launching the app via an entrypoint script lucas-chess)
• Makes the package build pick up all engines, Windows and Linux, to create a giant Python package.

Usage

Build the wheel and source distribution:

uv build

This will create 2 large files (a wheel and a source distribution) as a Python package:

$ ls -l dist/
-rw-r--r-- 1 peter users 407M 14. Sep 17:26 lucas_chess-2.20.0.dev0-py3-none-any.whl
-rw-r--r-- 1 peter users 405M 14. Sep 17:25 lucas_chess-2.20.0.dev0.tar.gz

Both resulting package files can directly be installed (in a virtual environment) via

uv pip install <package-filename>

Alternatively, you can install them from source off the GitHub repository directly via

uv pip install git+https://github.com/<username>/lucaschessR2@<branch>#egg=lucas-chess

Once the package is installed, the application can be run from the terminal via

lucas-chess

Alternatively, the application can still be run from source code like this:

uv run src/main.py

Notes

• This PR is based on the two PRs Add root-level pyproject.toml with dependencies #207 and Make engines executable via version control (Linux, macOS) #208. (When those two are merged this PR can be rebased and will then be much smaller.)
• The Python package must be installed using Python 3.8, otherwise lucas-chess will abort with a segmentation fault when executed. This is because the Manager.py module loads the FasterCode library, which is included as a pre-built library (apparently built with Python 3.8). With Python 3.8 a ModuleNotFoundError: No module named 'FasterCode' stops the startup, reported by the shiboken2 module.
• As discussed in Install Lucas Chess from PyPI (aka pip install lucas-chess) #203 (comment) it makes sense to refactor how the engines are loaded. It would also make sense to distribute the engines independently from the Python application.

[lukasmonk]

Thanks for the information, I will see if it is possible when the development of LucasChessR6 starts.
In LucasChessR2 I'm not going to make structural changes, first of all for fear of side effects.