domCreateElement treated SX NIL (a truthy JS object) as a real namespace,
calling createElementNS("nil", tag) instead of createElement(tag). All
elements created by resolveSuspense ended up in the "nil" XML namespace
where CSS class selectors don't match.
Also fix ~suspense fallback: empty &rest list is truthy in SX, so
fallback content never rendered.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>