- entry in profile menu, visible only while a device is connected
- live FFE4 readout: 7x PD, VBAT, fitting, scan wave marker, run state
- tap a face-map region to fire a 2s single-region treat command
(verifies region-to-IO mapping on the physical mask)
- wavelength selector (red/ir/uv/yellow) to verify color byte order
- scan command / full-face 2s / stop buttons, hex log of every write
- intentionally not i18n'd; remove page before release
