The zero-Janet spine proves the on-Chez analyzer/emitter compile arbitrary
Clojure faithfully. This proves the stronger property: the on-Chez compiler
reproduces itself. emit-image.ss re-emits the compiler sources (jolt.ir +
jolt.analyzer + jolt.backend-scheme) ON CHEZ via the loaded image; feeding it
stage1 (the Janet cross-compile) yields stage2, feeding stage2 yields stage3.
stage2 and stage3 are byte-for-byte identical, and stage2 is a working compiler
(real cases compile+run through it). stage1 differs from stage2 only in gensym
numbering, so the fixpoint is stage2==stage3.
driver: emit-image-on-chez / program-emit-image spawn a fresh chez per stage
(clean gensym state). test/chez/fixpoint-test.janet gates it (skips without chez).
