The heartbeat and activity LED each computed the PWM pulse inline.
zephcore_led_pwm_write() in led_gate.c now does it once.
Comments added for the LED work described branch history, dates and
release notes; keep only what the code needs. led_gate.c still said the
brightness was RAM-only, which is no longer true, and the server decode
comment gave the old 10% default.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>