python-pam imports six but doesn't declare it. On Linux, six is usually
present system-wide. On macOS uv tool environments (clean/isolated),
import pam fails with 'No module named six'. Adding six explicitly to
our deps ensures PAM auth works on macOS.
python-multipart is required by FastAPI for form POST handling (login).
Was missing from pyproject.toml — crash on macOS first run.
launchd plist now uses the muxplex entry point script directly instead
of python -m muxplex, so macOS shows 'muxplex' in Activity Monitor,
launchctl list, and login items instead of 'python3'.
Brian Krabach