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/jolt-chez.janet

@@ -23,6 +23,7 @@
            "host/chez/ns.ss" "host/chez/post-prelude.ss" "host/chez/natives-meta.ss"
            "host/chez/natives-str.ss" "host/chez/records.ss"
            "host/chez/host-class.ss" "host/chez/io.ss"
+           "host/chez/inst-time.ss"
            "host/chez/host-static.ss" "host/chez/dot-forms.ss"
            "src/jolt/clojure/string.clj" "src/jolt/clojure/walk.clj"
            "src/jolt/clojure/template.clj"]