Add pyproject.toml (Python >=3.13, no runtime dependencies, pytest, ruff
and mypy as dev extras), a Doxyfile that scans src/, the
src/coffee_machine package with stub constants and main modules, and a
pytest smoke test. Ignore Doxygen output in .gitignore.
Closes#1Closes#2Closes#3Closes#4
Refs #5
Task: MIL-001#1
Task: MIL-001#2
Task: MIL-001#3
Task: MIL-001#4