When morphing DOM after server fetch, the morph engine reuses elements
with the same tag. If old element was island A and new is island B,
syncAttrs updates data-sx-island but the JS property _sxBoundisland-hydrated
persists on the reused element. sx-hydrate-islands then skips it.
Fix: in morphNode, when data-sx-island attribute changes between old and
new elements, dispose the old island's signals and clear the hydration
flag so the new island gets properly hydrated.
New Playwright tests:
- counter → temperature navigation: temperature signals work
- temperature → counter navigation: counter signals work
- Direct load verification for both islands
- No JS errors during navigation
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>