Retranspile sx_ref.ml with mutable globals from transpiler

No more regex fixups for *strict* / *prim-param-types* — transpiler
handles reads (!_ref), writes (_ref :=), and defines natively.
2566/2568 tests pass.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

hosts/ocaml/lib/sx_ref.ml

@@ -296,18 +296,20 @@ and render_fn =
   Nil
 
 (* *strict* *)
-and _strict_ = !_strict_ref
+and _strict_ =
+  !_strict_ref
 
 (* set-strict! *)
 and set_strict_b val' =
-  _strict_ref := val'; Nil
+  let _strict_ = ref Nil in (_strict_ref := val'; Nil)
 
 (* *prim-param-types* *)
-and _prim_param_types_ = !_prim_param_types_ref
+and _prim_param_types_ =
+  !_prim_param_types_ref
 
 (* set-prim-param-types! *)
 and set_prim_param_types_b types =
-  _prim_param_types_ref := types; Nil
+  let _prim_param_types_ = ref Nil in (_prim_param_types_ref := types; Nil)
 
 (* value-matches-type? *)
 and value_matches_type_p val' expected_type =