Fix last 2 foreign-type-checking tests: ListRef match + #t→true

- run_tests.ml: foreign-check-args binding now matches ListRef (from
  the list primitive) in addition to List
- test-foreign.sx: replace #t with true in guard clauses — SX parser
  treats #t as a symbol, not a boolean

2800/2800 tests, zero failures.

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

hosts/ocaml/bin/run_tests.ml

@@ -636,7 +636,12 @@ let make_test_env () =
   bind "foreign-names" (fun _args -> Sx_ref.foreign_names ());
   bind "foreign-register!" (fun args -> match args with [String n; spec] -> Sx_ref.foreign_register_b (String n) spec | _ -> Nil);
   bind "foreign-resolve-binding" (fun args -> match args with [String s] -> Sx_ref.foreign_resolve_binding (String s) | _ -> Nil);
-  bind "foreign-check-args" (fun args -> match args with [String n; List p; List a] -> Sx_ref.foreign_check_args (String n) (List p) (List a) | _ -> Nil);
+  bind "foreign-check-args" (fun args ->
+    let to_list = function List l -> List l | ListRef r -> List !r | v -> v in
+    match args with
+    | [String n; (List _ | ListRef _ as p); (List _ | ListRef _ as a)] ->
+      Sx_ref.foreign_check_args (String n) (to_list p) (to_list a)
+    | _ -> Nil);
   bind "foreign-build-lambda" (fun args -> match args with [spec] -> Sx_ref.foreign_build_lambda spec | _ -> Nil);
 
   (* Initialize CEK call forward ref — needed by with-capabilities and foreign-dispatch *)