usb_query.py 267 -> 180. The non-blocking fd handling - _drain_buffer,
_write_with_deadline, _read_nonblocking, _wait_for_pjl_response and
pjl_query - moves to _pjl_io.py.
usb_query imports the three names test_usb_query.py patches back, which
is safe here only because all three still have real call sites in the
code that stayed; an import-only name would be stripped by ruff's F401
sweep and break the patch. os and time also stay: they are patched on
usb_query as well as on _pjl_io.
test_usb_query.py needs no edit. Pass count is 402 before and after.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011w2Pj4Ek3ZNMQVYcFHgXDY
