MEP-56 note 04: Runtime building blocks

Author: research pass for MEP-56 (Mochi to Ruby transpiler). Date: 2026-05-29 (GMT+7).

CRuby 3.2+ stdlib primitives used by mochi-runtime: Thread, Thread::SizedQueue, Fiber, Data.define, Enumerator::Lazy, net/http, json, set, bigdecimal, stringio, tempfile, digest/sha256.

Full research note content for MEP-56 note 04.