malloc-bench-rs 0.1.0

Portable, 100% Rust, generic-over-GlobalAlloc multi-threaded allocator benchmark harness (larson + mstress workloads with cross-thread handoff). The pure-Rust answer to mimalloc-bench (which is C-only) — zero runtime dependencies, comparison crates like mimalloc/jemalloc remain dev-only at consumer's discretion.