docs/SAFETY.md documents the control board's laser safing chain as
reverse-engineered and bench-verified - parts, every net with its SoC pin,
Linux exposure and polarity, the logic, and the software layers ForgeFIRM
stacks on it - with docs/img/safety-chain.svg. Linked from the README.
BRINGUP: Next work item 11 records the interlock-latch finding (an open
loop never tripped the latch; the kernel now drives INTERLOCK_LATCH_RESET)
and the charge-pump watchdog readback, both code-complete and pinned,
bench validation on the next image.
