fix(parser): read_edn returns first form, matching cljs read-string

Upstream cljs tools.reader/read-string and cljs.reader/read-string both
return the first parsed form and ignore trailing input; the strict EOF
check rejected inputs cljs accepts (e.g. quote-wrapped query strings
truncated by inner quotes).

Author: tiensonqin

impl/parser.ml

@@ -295,9 +295,9 @@ let read_edn input =
       Buffer.add_char buffer char;
       parse_string (index + 1) buffer
   in
-  let form, index = parse_form 0 in
-  if skip index <> length then invalid_arg "trailing EDN input";
-  form
+  (* cljs tools.reader/read-string semantics: parse the first form and
+     ignore trailing input — upstream never checks EOF. *)
+  fst (parse_form 0)
 
 let rec query_value_of_form = function
   | QueryFormNil -> Nil