[python-compat] Python 3.11 support blocked on cpppo library

[ethan-thomason]

The cpppo library used for EtherNet/IP emulation breaks on Python 3.11. Options under investigation: find a maintained cpppo fork, replace with pycomm3, or stub EtherNet/IP temporarily. See ROADMAP.md Phase 2.

[ethan-thomason]

Status update: currently pinned to Python 3.10 via .python-version. uv + black toolchain confirmed working on 3.10. Unblocking 3.11+ requires replacing cpppo which has no maintained Python 3.11 compatible version. Leaving open pending research into alternatives.