Fix &rest param binding in OCaml evaluator + clean test suite: 0 failures

OCaml evaluator: has_rest_param and bind_lambda_params checked for
String "&rest" but the parser produces Symbol "&rest". Both forms now
accepted. Fixes swap! extra args (signal 10 → swap! s + 5 → 15).

test-adapter-html.sx: fix define shorthand → explicit fn form, move
defcomp/defisland to top level with (test-env) for component resolution.

2515 passed, 0 failed.

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

hosts/ocaml/lib/sx_ref.ml

@@ -296,9 +296,10 @@ and strict_check_args name args =
 and bind_lambda_params params args local =
   (* Check for &rest in param list *)
   let param_strs = sx_to_list params in
+  let is_rest_marker = function String "&rest" | Symbol "&rest" -> true | _ -> false in
   let rec find_rest idx = function
     | [] -> None
-    | String "&rest" :: rest_name :: _ -> Some (idx, rest_name)
+    | x :: rest_name :: _ when is_rest_marker x -> Some (idx, rest_name)
     | _ :: tl -> find_rest (idx + 1) tl
   in
   match find_rest 0 param_strs with
@@ -313,7 +314,7 @@ and bind_lambda_params params args local =
 
 and has_rest_param params =
   let param_strs = sx_to_list params in
-  List.exists (function String "&rest" -> true | _ -> false) param_strs
+  List.exists (function String "&rest" | Symbol "&rest" -> true | _ -> false) param_strs
 
 and call_lambda f args caller_env =
   (let params = (lambda_params (f)) in let local = (env_merge ((lambda_closure (f))) (caller_env)) in