Chez Phase 2 (inc X): #inst / #uuid literals + java.time (jolt-at0a)

The analyzer lowers a #inst/#uuid tagged form to a :inst/:uuid IR leaf, mirroring
the existing :regex node: the Janet back end punts to the interpreter (its
data-readers parse the literal, so seed behavior is unchanged), the Chez back end
emits jolt-inst-from-string / jolt-uuid-from-string.

host/chez/inst-time.ss is the Chez-native value layer: a jinst record holding
epoch ms (RFC3339 parsed via Hinnant civil/days math, with Clojure's partial
defaults and +/-hh:mm offsets), wired into jolt-get (so the overlay inst?/inst-ms
read it), jolt= / jolt-hash (instant identity as a map key), pr-str (#inst
"...-00:00"), str, type, and instance? java.util.Date. The java.time surface
(DateTimeFormatter ofPattern/ISO_LOCAL_DATE_TIME/ofLocalized*, the pattern engine,
Instant, ZoneId, LocalDateTime, FormatStyle, Locale, Date) ports java_base.janet
over host-static.ss's registries.

Corpus 2202->2238, 0 new divergences; clears the whole 'unsupported form'
emit-fail bucket. Full Janet gate green (analyzer/backend changes are
behaviour-preserving — #inst still parses through the interpreter's data-readers
on the seed).

host/chez/rt.ss

@@ -293,3 +293,9 @@
 ;; arm wraps the fully-built record-method-dispatch and the str/type/instance-check
 ;; extensions sit over every prior shim.
 (load "host/chez/io.ss")
+
+;; #inst values + java.time formatting (jolt-at0a inc X): jinst (RFC3339 ms) +
+;; DateTimeFormatter/Instant/ZoneId/LocalDateTime/FormatStyle/Locale/Date. Loads
+;; LAST — it extends record-method-dispatch / jolt-get / jolt= / jolt-hash /
+;; jolt-pr-str / jolt-type / instance-check and uses host-static.ss's registries.
+(load "host/chez/inst-time.ss")