First fractal turn of the multi-stage bootstrap (jolt-tzo). The Clojure part of
clojure.core is now loaded in ordered tiers under jolt-core/clojure/core/. The
kernel tier (00-kernel: second/peek/subvec/mapv/update) holds the structural fns
the self-hosted compiler itself uses; in compile mode it is bootstrap-compiled
into clojure.core BEFORE the analyzer is built, so the analyzer binds those names
to the Clojure definitions instead of a not-yet-defined forward ref. That removes
the circularity that previously forced these to stay in Janet — the five core-*
primitives and their init-core! entries are gone.
Mechanism: backend/bootstrap-load-source (generalized from compile-load) builds a
source string into a target ns via the bootstrap; rebuild-compiler! recompiles
the self-hosted compiler against the current core (the rail for future turns,
exercised by the new fixpoint test). api/load-core-overlay! walks the ordered
tiers, bootstrap-loading kernel tiers and self-hosting the rest.
Also fixes a latent evaluator bug surfaced by the move: a fn rebinds current-ns
to its defining ns while it runs and restores on normal return, but a fn that
THREW unwound past its own restore, leaking the ns. try now restores the
try-entry ns on the catch/finally path, so referred-symbol resolution survives a
caught error (this was breaking is/testing in the suite harness after any thrown
assertion). Net battery +3 (3913 -> 3916); conformance 218/218 in all three
modes; binary builds and runs the embedded tiers.
