linting

A harmless-looking ruff sweep touched runtime aliases, TYPE_CHECKING boundaries, isort classification, and the Docker build layout all at once.

TL;DR: A harmless-looking lint commit shipped runtime import moves, type-checking guards, and a new pyproject.toml in one package. Only the last piece broke CI, because setuptools' flat-layout discovery choked on the leftover build directory the Docker install created. The fix: exclude build artifacts in ruff config and clean them within the same RUN instruction.