This PR adds Nix support for EOS, making it easy to build, run, and modify the project on Nix/NixOS without manually managing Python dependecies.

• Adds Nix packaging files:
  • flake.nix exposing:
    • packages.eos / packages.default (nix build .#eos)
    • apps.default (nix run .#eos -- …)
    • devShells.default (nix develop)
  • package.nix providing a reproducible Python application build (setuptools) with runtime deps.
  • shell.nix providing a simple dev shell for non-flake workflows (nix-shell).
  • flake.lock pinning nixpkgs/flake-utils for reproducibility.
• Fixes Python 3.12+ compatibility:
  • Replaces distutils.version.LooseVersion usage in eos/utils/version.py (removed from stdlib in Python 3.12+) with a small internal version comparator sufficient for EOS’ Symfony version comparisons.

Why:

• EOS is a CLI tool with a small dependency set, and Nix makes installs reproducible and isolated.
• Current upstream code relied on distutils, which breaks imports on modern Python (3.12+), and Nixpkgs commonly uses 3.12/3.13/3.14.

How to use / test:

• Build:
  • nix build .#eos
• Run:
  • nix run .#eos -- -h
• Dev environment:
  • nix develop
  • (non-flake alternative): nix-shell

Notes:

• package.nix builds EOS as a Python application and wraps the eos entrypoint.
• flake.lock is included so users get consistent results across systems.

Files changed:

• Added: flake.nix, flake.lock, package.nix, shell.nix
• Updated: eos/utils/version.py, .gitignore