PyPI-ready metadata (donglora-mux), full classifiers, URLs. Fixed dependency path to client-py. Added 11 interception tests ported from the Rust mux (SetConfig locking, StartRx/StopRx refcounting). GitHub Actions CI. Strict ruff linting. Applied contextlib.suppress per SIM105, collapsed nested ifs per SIM102. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>