fwcamctl provides userland access to /dev/fwcam0. Supported
subcommands: info (camera state, format, mode, rate, features),
snap (capture a frame as PPM), mode (set format/mode/rate), and
feat (get/set camera feature registers).
snap converts YUV422, YUV411, YUV444, RGB8, and Mono8 pixel
formats to RGB24 PPM with no external dependencies. A configurable
frame skip (default 5) allows auto-exposure and auto-white-balance
to settle before capture.