Makes the inc8 fixpoint the actual build. host/chez/bootstrap.ss loads a seed
(prelude, image) pair and rebuilds the clojure.core prelude + compiler image from
source via the on-Chez compiler — read/analyze/emit all on Chez, zero Janet.
The seed (host/chez/seed/{prelude,image}.ss) is the checked-in bootstrap
compiler, minted once via the fixpoint (driver/mint-chez-seed* iterates
bootstrap.ss from the Janet-emitted pair to a joint byte-fixpoint). It's a joint
fixpoint: rebuilding from an up-to-date seed reproduces it exactly. So a fresh
checkout + Chez (no Janet) yields a working jolt.
test/chez/bootstrap-test.janet spawns only chez, asserts the rebuilt artifacts
match the seed byte-for-byte and compile+run real cases. Drift (seed sources
changed) fails the test with a re-mint pointer; host/chez/seed/README documents
re-minting.
