writes raw bytes to /dev/lp0 (overridable via PRINTER_DEV): resets the
printer with ESC @, converts LF to CRLF to avoid staircasing on raw
device writes, then form-feeds to eject the page.
replaced the guvcview+keypress capture flow with a continuous
capture/convert/display loop so the terminal shows a live ascii
preview; pressing c saves the frame and triggers the new
txt2printr.sh hook (currently a blank template).