0e9d9d7d5f
Hand-rolled context switching on mmap'd stacks with guard pages, allocator-driven RDTSC preemption, unbounded MPSC channels, supervision via per-slot Signal mailboxes, root supervisor as sentinel PID. Lib + tests + benches clean check/clippy. All 29 tests pass. Bench: smarm 3.4% over serial baseline, within 160us of tokio current-thread on prime-counting fan-out.