Fix create-text-node in DOM adapter: host handle Dicts are DOM nodes

The DOM adapter treated all Dict values as empty (create-fragment).
But DOM nodes (text nodes, elements) from create-text-node/host-call
are wrapped as Dict { __host_handle: N } by js_of_ocaml. Now checks
for __host_handle and passes them through as DOM nodes.

Fixes stopwatch button text ("Start") and timer display ("0.0s")
which were missing because create-text-node results were discarded.

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

shared/static/wasm/sx/adapter-dom.sx

@@ -75,8 +75,10 @@
                         (scope-emit! "element-attrs" (spread-attrs expr)))
                       expr)
 
-      ;; Dict → empty
-      "dict"      (create-fragment)
+      ;; Dict → check for host DOM node, else empty fragment
+      "dict"      (if (has-key? expr "__host_handle")
+                    expr  ;; Host DOM node (text node, element, etc.) — pass through
+                    (create-fragment))
 
       ;; List → dispatch
       "list"

web/adapter-dom.sx

@@ -75,8 +75,10 @@
                         (scope-emit! "element-attrs" (spread-attrs expr)))
                       expr)
 
-      ;; Dict → empty
-      "dict"      (create-fragment)
+      ;; Dict → check for host DOM node, else empty fragment
+      "dict"      (if (has-key? expr "__host_handle")
+                    expr  ;; Host DOM node (text node, element, etc.) — pass through
+                    (create-fragment))
 
       ;; List → dispatch
       "list"