b3d8a21b72
And default ignore_thread_priorities to false. Map Xenon's 0-31 priority range across all 5 host priority levels instead of collapsing 0-17 into kNormal. Use timer-driven quantum decay (~20ms period) matching Xenon's 60-quantum / 3-per-tick cycle to prevent starvation by gradually lowering effective priority for non-real-time threads (< 18), piggybacking on the existing 1ms timestamp timer.