Meta unarchives jemalloc, resumes active stewardship

Meta’s "un-abandonment" of jemalloc signals that foundational infrastructure requires fresh engineering to keep pace with custom silicon and modern kernel behaviors. Priority support for AArch64 reflects the industry-wide shift toward ARM-based hardware, while the new Huge-Page Allocator aims to solve the trade-off between CPU efficiency and memory fragmentation. Unarchiving the repository rebuilds trust after years of stagnation, reinforcing jemalloc's role as a scalability benchmark despite competition from Microsoft's mimalloc.