bdwidth reads its CH340 from a reactor timer without error handling, so
"write failed: [Errno 5] Input/output error" shut down Klipper mid print.
bdwidth_status now wraps the sensor's Read_bdwidth (bdwidth.py itself
unchanged): on a USB error it closes the port, reports once and returns
False, so bdwidth retries every 10 s; the port is reopened when the
device is back. New status fields usb_ok and usb_errors.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
