Fix: RGBIC segment race condition on area-targeted turn_off (#16)
When light.turn_off targets a Home Assistant area containing an RGBIC device, all light entities (main + segments) receive concurrent turn_off calls via asyncio.gather. The segment entities could check the _pending_power_off flag before the main entity had a chance to set it, causing conflicting API commands and firmware glitches.
Fix: Add await asyncio.sleep(0) at the start of segment async_turn_off() to yield to the event loop, ensuring the main entity's PowerCommand sets the flag before any segment checks it. Zero real-time cost (one event loop cycle).