Islands now clear SSR children before render-to-dom and append the
fresh DOM result. Avoids hydrate-mismatch errors from SSR/client
attribute differences (~tw generates different class strings).
The hydrating scope is set to nil (no cursor walk) so render-to-dom
creates new DOM nodes instead of trying to reuse SSR elements.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>