Bump virt ulimit to 256G; revert pigz -1 -> pigz -9
The 96G ulimit -v killed 1500-node sims at slot 313 with RSS only at 58G — Rust+tokio allocator reserves more virtual address space on larger topologies than physical commit alone implies. The cap was sized for 750 nodes; 1500 needs more headroom. 256G is the board's max physical RAM ceiling; actual commit is bounded by RAM + swap. Reverts pigz -1 to pigz -9 — the faster compressor did not solve the end-of-sim EventMonitor spike (still ~8 GB from 11M events flushed at once, regardless of compressor speed). The bottleneck is the unbounded mpsc channel, not compression. Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>