Power-bytes-only program played by the pulse engine with the scope on
LASER_PWM: full duty staircase observed, run-start 100 percent duty
reset confirmed on the pin, consecutive-power-byte drop confirmed
(second byte of a back-to-back pair discarded), and duty persists
after end-of-data - the laser-off guarantee rests entirely on FIRE.
Zero motion (motor_lock=15 + no step bytes; position counters pinned)
and the laser chain silent throughout. Adds pwm_stream_test.py to the
bench kit and records the FIRE/OK_2_FIRE/LASER_ON/HV_EN naming from
the OpenGlow LASER SAFING sheet.
