Chez Phase 2 (inc R): . / .-field dot-form desugar (jolt-kuic)

The analyzer lowers the `.` special form (. target member arg*) and the
.-field field-access head to a :host-call instead of leaving them
uncompilable. Janet behaviour is unchanged — its back end punts :host-call
to the interpreter, which re-runs the original `.` form via eval-dot.

The Chez back end routes a non-shimmed :host-call through
record-method-dispatch, extended by a new host/chez/dot-forms.ss with the
arms dispatch-member covers but the record/string base did not, mirroring
src/jolt/interop/collections.janet precedence:

  - collection interop first (count/seq/nth/get/valAt/containsKey on a
    vector/map/set), so (. {:count 9} count) is the entry count like the seed
  - field access for a "-name" member (records and maps)
  - the seed's universal object-methods (getMessage/getCause/toString/
    hashCode/equals) on a non-record map, winning over a field lookup
  - non-record map member: a stored fn is a method called with self, else
    the field value

Raw seqs are excluded from coll interop — the seed's behaviour there is
representation-dependent (plain (seq v) vs a lazy-seq) and a normalized cseq
can't mirror it. Also added getMessage/getLocalizedMessage/equals to the
string method surface so a thrown string / Exception. ctor (which keeps the
message string) answers .getMessage.

Parity 2134 -> 2150, 0 new divergences. New test/chez/_dotform.janet 26/26;
emit-test 331/331.

test/chez/_dotform.janet

@@ -0,0 +1,70 @@
+# jolt-kuic — the `.` special form + `.-field` field-access desugar on Chez. The
+# analyzer lowers (. target member arg*) and (.-field target) to a :host-call;
+# the Chez emit routes a non-shimmed :host-call through record-method-dispatch,
+# which dot-forms.ss extends with field access + map/vector member dispatch.
+# Expectations are the build/jolt (seed) oracle, captured per case.
+#
+#   janet test/chez/_dotform.janet
+(def jolt-bin (or (os/getenv "JOLT_BIN") "bin/jolt-chez"))
+
+(def exprs
+  [# strings: method calls via the String surface
+   "(. \"HI\" toLowerCase)"
+   "(. \"abc\" length)"
+   "(. \"abc\" toUpperCase)"
+   # vectors / maps: collection interop (count/nth/get/containsKey)
+   "(. [1 2 3] count)"
+   "(. [10 20 30] nth 1)"
+   "(. {:a 1 :b 2} count)"
+   "(. {:a 1 :b 2} get :b)"
+   "(. {:a 1} containsKey :a)"
+   "(. {:count 99} count)"
+   # map member: stored fn called with self (+ args), else field value
+   "(. {:value 41 :describe (fn [self] (str \"v=\" (:value self)))} describe)"
+   "(. {:greet (fn [self n] (str \"Hello \" n))} greet \"Alice\")"
+   "(. {:value 41} value)"
+   # field access via .-field head
+   "(.-value {:value 41})"
+   "(.-x {:x 7 :y 9})"
+   # field access via (. obj -field)
+   "(. {:value 41} -value)"
+   # records: .-field reads a field, .method dispatches the protocol method
+   "(do (defrecord Rf [x]) (.-x (->Rf 7)))"
+   "(do (defrecord Rg [a b]) (.-b (->Rg 1 2)))"
+   "(do (defprotocol Greet (hi [_])) (defrecord Rh [nm] Greet (hi [_] (str \"hi \" nm))) (. (->Rh \"x\") hi))"
+   # universal object-methods on a non-record map win over a field lookup
+   "(try (throw (ex-info \"bad\" {})) (catch Throwable e (.getMessage e)))"
+   "(try (throw (ex-info \"bad\" {:k 1})) (catch Throwable e (.getMessage e)))"
+   "(try (throw \"boom\") (catch Throwable e (.getMessage e)))"
+   "(try (throw (Exception. \"boom\")) (catch Throwable e (.getMessage e)))"
+   "(try (throw (IllegalArgumentException. \"bad\")) (catch Exception e (.getMessage e)))"
+   "(.equals \"a\" \"a\")"
+   "(.equals \"a\" \"b\")"
+   "(. {:value 41 :describe (fn [self] (str \"v=\" (:value self)))} describe)"])
+
+(defn run-capture [bin expr]
+  (def proc (os/spawn [bin "-e" expr] :p {:out :pipe :err :pipe}))
+  (def out (ev/read (proc :out) 0x100000))
+  (def err (ev/read (proc :err) 0x100000))
+  (def code (os/proc-wait proc))
+  (def lines (filter (fn [l] (not (empty? l)))
+                     (string/split "\n" (string/trim (if out (string out) "")))))
+  [code (if (empty? lines) "" (last lines)) (string/trim (if err (string err) ""))])
+
+(var pass 0)
+(def fails @[])
+(each expr exprs
+  (def [ocode oracle _] (run-capture "build/jolt" expr))
+  (def [code got err] (run-capture jolt-bin expr))
+  (cond
+    (not= ocode 0) (array/push fails [expr (string "ORACLE FAILED exit " ocode)])
+    (not= code 0) (array/push fails [expr (string "exit " code "; err: " err)])
+    (= got oracle) (++ pass)
+    (array/push fails [expr (string "want `" oracle "`, got `" got "`")])))
+
+(printf "\n_dotform parity [%s]: %d/%d passed" jolt-bin pass (length exprs))
+(when (> (length fails) 0)
+  (printf "%d FAIL(s):" (length fails))
+  (each [e m] fails (printf "  FAIL %s\n    %s" e m)))
+(flush)
+(os/exit (if (empty? fails) 0 1))