HS: hyperscript:beforeFetch event + runner dict format (+1 test)

- hs-fetch gains target param; dispatches hyperscript:beforeFetch before fetch
- compiler emits (quote me) as target arg
- runner io-fetch returns unified dict {_type:'dict', ok, status, _body, ...}
  so runtime (get raw :key) calls work correctly (22/23 fetch tests pass)

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

lib/hyperscript/runtime.sx

@@ -874,12 +874,15 @@
 (define
   hs-fetch
   (fn
-    (url format do-not-throw)
+    (url format do-not-throw target)
     (let
       ((fmt (cond ((nil? format) "text") ((or (= format "json") (= format "JSON") (= format "Object")) "json") ((or (= format "html") (= format "HTML")) "html") ((or (= format "response") (= format "Response")) "response") ((or (= format "text") (= format "Text")) "text") ((or (= format "number") (= format "Number")) "number") (true format))))
-      (let
-        ((raw (perform (list "io-fetch" url "response" (dict)))))
-        (do
+      (do
+        (when (not (nil? target))
+          (dom-dispatch target "hyperscript:beforeFetch" nil))
+        (let
+          ((raw (perform (list "io-fetch" url "response" (dict)))))
+          (do
           (when (get raw :_network-error) (raise {:response raw :message "Network error" :_hs-error "FetchError"}))
           (when
             (and (not (get raw :ok)) (not (= fmt "response")) (not do-not-throw))
@@ -897,7 +900,7 @@
                 (parse-number (get raw :_number))
                 (parse-number (get raw :_body))
                 0))
-            (true (get raw :_body))))))))
+            (true (get raw :_body)))))))))
 
 (define
   hs-json-escape