The DMR RX handler re-asserts the green LED whenever it reads it off, racing the
main-loop mute clear, so green flickered between the red flashes. Add a
LedGreenSuppress() hold in the LED driver: while muted the green LED is forced
off (the re-assert becomes a no-op); on un-mute the hold is released and green is
restored from the current RX state.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>