The step backend now lives in github.com/ScottW514/grblHAL-glowforge
(grblHAL driver convention: core submodule, driver.c HAL, board header).
Add build-glowforge.sh, update the BRINGUP runbook (no -t throttle,
EEPROM path, kill-before-scp, producer stats line, reset/disconnect
semantics), and teach bench_m2.py to parse the F: status field (no
spindle registered = no FS: field). Settings-write crash fix is
upstream as grblHAL/core PR 999.
