Maps slot -> block device via /sys/class/enclosure/, joins lsblk size/model
and zpool membership, renders a text table plus a colored cols x rows grid
of the physical shelf (slot 0 top-left, left to right). Geometry is
configurable via COLS/ROWS env vars; default 6x4 fits a 24-bay shelf.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>