feat(keymap): photorealistic N0120 device rendering

Rework the calculator mockup to match the NumWorks industrial design:
white plastic shell with wordmark, amber-barred LCD readout, cross
d-pad, amber Home / dark power / round OK & Back, oval keycaps with
per-category rails. Keeps click cross-highlighting, key/command views,
and the dashed-coral emphasis on unused keys.

Author: 1e1