refactor: registry pattern for jolt-pr-str/pr-readable + remaining arms (jolt-lmot)

The printer's two entry points (jolt-pr-str in rt.ss, jolt-pr-readable in printing.ss)
get register-pr-str-arm! / register-pr-readable-arm!, plus register-pr-arm! for the
types whose str and readable forms match (bigdec/inst/uuid/tagged/record/ns/var). The
normalize arms (sorted, lazy-seq, queue) and the uri readable arm register per-printer.
Also folds in the hash (dyn-binding var-cell), class (io uri/uuid/file), and get
(transients) arms missed earlier.

natives-array's get stays a case-lambda wrapper on purpose: its 2-arg path errors on
an out-of-bounds index while the 3-arg path returns the default, an arity distinction
the (coll k d) registry collapses — left as-is to preserve behaviour.

Completes jolt-lmot: all six dispatchers (hash/class/get/=/pr-str/pr-readable) off the
set!-rebind chains. make test green, 0 new corpus divergences; pr-str/str of inst,
uuid, bigdec, sorted-map, record-with-lazyseq, queue all verified.

host/chez/dyn-binding.ss

@@ -132,12 +132,7 @@
 ;; var-cell keys hash/compare by ns/name (jolt=2 in vars.ss already compares
 ;; ns/name) — stable under root mutation, so a var works as a map key (with-redefs
 ;; builds (hash-map (var f) v); get-thread-bindings returns a var-keyed map).
-(define %dyn-hash jolt-hash)
-(set! jolt-hash
-  (lambda (x)
-    (if (var-cell? x)
-        (equal-hash (cons (var-cell-ns x) (var-cell-name x)))
-        (%dyn-hash x))))
+(register-hash-arm! var-cell? (lambda (x) (equal-hash (cons (var-cell-ns x) (var-cell-name x)))))
 
 ;; --- bind the host seams the overlay references -----------------------------
 (def-var! "clojure.core" "push-thread-bindings" jolt-push-thread-bindings)