- test_nano: every hex digit of B data is one drawDots() call, never single
drawPixel() calls (the slow path that broke dense images in 2.19.2)
- tools/display_smoke_test.py: all yellow, a dense image and a checkerboard
in live mode on the real display; fails on any frame check problem (wrong
image, no answer, Nano restart, ERR reply)
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
