spec: multiple values — values/call-with-values/let-values/define-values

25 tests pass on both JS and OCaml hosts. Uses dict marker
{:_values true :_list [...]} for 0/2+ values; 1 value passes
through directly. step-sf-define extended to desugar shorthand
(define (name params) body) forms on both hosts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hosts/ocaml/bin/run_tests.ml

@@ -1120,6 +1120,27 @@ let make_test_env () =
     | _ :: _ -> String "confirmed"
     | _ -> Nil);
 
+  bind "values" (fun args ->
+    match args with
+    | [v] -> v
+    | vs ->
+      let d = Hashtbl.create 2 in
+      Hashtbl.replace d "_values" (Bool true);
+      Hashtbl.replace d "_list" (List vs);
+      Dict d);
+
+  bind "call-with-values" (fun args ->
+    match args with
+    | [producer; consumer] ->
+      let result = Sx_ref.cek_call producer (List []) in
+      let spread = (match result with
+        | Dict d when (match Hashtbl.find_opt d "_values" with Some (Bool true) -> true | _ -> false) ->
+          (match Hashtbl.find_opt d "_list" with Some (List l) -> l | _ -> [result])
+        | _ -> [result])
+      in
+      Sx_ref.cek_call consumer (List spread)
+    | _ -> raise (Eval_error "call-with-values: expected 2 args"));
+
   env
 
 (* ====================================================================== *)