HS: route hide through hs-hide! runtime (dialog/details support)

Mirrors hs-show! pattern — dialog calls close(), details sets open=false.
No test count change (custom strategy tests need behavior system).

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

lib/hyperscript/runtime.sx

@@ -497,6 +497,20 @@
         (host-call el "close")
         (dom-set-prop el "open" false)))))
 
+(define
+  hs-hide!
+  (fn
+    (el strategy)
+    (let
+      ((tag (dom-get-prop el "tagName")))
+      (cond
+        ((= tag "DIALOG")
+          (when (dom-has-attr? el "open") (host-call el "close")))
+        ((= tag "DETAILS") (dom-set-prop el "open" false))
+        ((= strategy "opacity") (dom-set-style el "opacity" "0"))
+        ((= strategy "visibility") (dom-set-style el "visibility" "hidden"))
+        (true (dom-set-style el "display" "none"))))))
+
 (define
   hs-show!
   (fn