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>