1. partition+concat removed from 10-seq.clj overlay — they use
lazy-seq macro which produces raw make-lazy-seq forms in compile
mode (same issue as mapcat overlay reversal). Must stay native.
2. Dead defns removed from core.janet: core-map-indexed,
core-iterate, core-repeatedly (30 lines). Bindings already
removed in prior commit.
3. dedupe removed from 40-lazy.clj — belongs in 20-coll.clj.
Gates: conformance 229×3, lazy-infinite 22/22, specs 32/32.
a71bddd580