The streaming shell now uses render_to_html so [data-suspense] elements
are real DOM elements immediately when the browser parses the HTML.
Previously the shell used SX wire format in a <script data-mount> tag,
requiring sx-browser.js to boot and render before suspense elements
existed — creating a race condition where resolution scripts fired
before the elements were in the DOM.
Now: server renders HTML with suspense placeholders → browser has real
DOM elements → resolution scripts find and replace them reliably.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>