Preserve pre-existing WIP from master's working tree. When a project
has a uv.lock alongside pyproject.toml, run pip-audit and pytest under
`uv run --directory $project` so they execute in the project's own
managed venv instead of whatever pytest/pip-audit happens to be on PATH.
Lifted verbatim from master's uncommitted working tree; committed on
this branch as the base for subsequent Bug B (tests.sh SIGPIPE) and
Bug C (pip-audit venv) fixes which both modify these regions.
