Step-by-step plan for jolt-c09 (Phase 5 of the clojure.core migration):
current state of the LazySeq machinery and the eager gaps, the cardinal
laziness rules, leaf-first transformer conversion order, realization-boundary
audit, the representation decision (lazy-seq vs eager-vector for map over a
vector), and a testing strategy built around a deadlined subprocess harness
(infinite realizations are CPU-bound and uninterruptible in-process).
