HS E36: socket URL parsing + hs-socket-register! runtime (+3 tests)

- parser.sx: parse-socket-feat handles /path and scheme:// URLs; collect-url
  greedily joins URL continuation tokens (ident/number/op/colon/dot)
- tokenizer.sx: fix :// not treated as line comment (lookback check)
- compiler.sx: emit-socket compiles socket AST to hs-socket-register! call
- runtime.sx: hs-socket-register! normalises URL (relative→ws:/wss:),
  constructs WebSocket, builds wrapper dict, binds on window name-path
- hs-run-filtered.js: WebSocket mock uses plain object (not JS array) so
  host-global returns a foreign value rather than SX list; host-get idx works

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

lib/hyperscript/parser.sx

@@ -2733,7 +2733,6 @@
         parse-socket-feat
         (fn
           ()
-          ;; Collect name-path: ident (class)* → e.g. ["Foo"] or ["MyApp" "chat"]
           (let
             ((seg0 (tp-val)))
             (adv!)
@@ -2750,7 +2749,6 @@
                   acc)))
             (let
               ((name-path (collect-segs (list seg0))))
-              ;; url-cont?: token types that can appear inside a URL
               (define
                 url-cont?
                 (fn
@@ -2769,7 +2767,6 @@
                           (= (tp-val) "with")
                           (= (tp-val) "on")
                           (= (tp-val) "as")))))))
-              ;; collect-url: accumulate URL tokens into a joined string
               (define
                 collect-url
                 (fn
@@ -2781,51 +2778,12 @@
                       (adv!)
                       (collect-url (append parts (list v))))
                     (join "" parts))))
-              ;; Parse URL: /path, scheme://..., string literal, or expression
               (let
-                ((url
-                  (cond
-                    ;; Relative path starting with /
-                    ((and (= (tp-type) "op") (= (tp-val) "/"))
-                      (adv!)
-                      (collect-url (list "/")))
-                    ;; Absolute URL: ident + colon → collect as scheme:rest
-                    ((= (tp-type) "ident")
-                      (let
-                        ((scheme (tp-val)))
-                        (adv!)
-                        (if
-                          (= (tp-type) "colon")
-                          (collect-url (list scheme))
-                          (parse-arith (parse-poss (list (quote ref) scheme))))))
-                    ;; String literal or other expression
-                    (true (parse-atom)))))
-                ;; Optional: with timeout <expr>
+                ((url (cond ((and (= (tp-type) "op") (= (tp-val) "/")) (do (adv!) (collect-url (list "/")))) ((= (tp-type) "ident") (let ((scheme (tp-val))) (adv!) (if (= (tp-type) "colon") (collect-url (list scheme)) (parse-arith (parse-poss (list (quote ref) scheme)))))) (true (parse-atom)))))
                 (let
-                  ((timeout-ms
-                    (if
-                      (match-kw "with")
-                      (do
-                        (adv!)
-                        (parse-expr))
-                      nil)))
-                  ;; Optional: on message [as JSON] <cmd-list>
+                  ((timeout-ms (if (match-kw "with") (do (adv!) (parse-expr)) nil)))
                   (let
-                    ((on-msg
-                      (if
-                        (match-kw "on")
-                        (do
-                          (adv!)
-                          (let
-                            ((json?
-                              (if
-                                (match-kw "as")
-                                (do (adv!) true)
-                                false)))
-                            (let
-                              ((body (parse-cmd-list)))
-                              (list (quote on-message) json? body))))
-                        nil)))
+                    ((on-msg (if (match-kw "on") (do (adv!) (let ((json? (if (match-kw "as") (do (adv!) true) false))) (let ((body (parse-cmd-list))) (list (quote on-message) json? body)))) nil)))
                     (match-kw "end")
                     (list (quote socket) name-path url timeout-ms on-msg))))))))
       (define