Hojun-Cho
fa33357821
Replaces rt_alloc-per-cell (one 4 KiB mmap each) with arena_alloc over 64 KiB chunks. test_huge peak under massif --pages-as-heap=yes drops from ~525 MB to ~253 MB. Same lifetime semantics; remaining bulk is per-call append() in eval's arg slice (rt_ensure still mmaps page-per-call).