Client-side routing was only swapping #main-panel content without
updating OOB headers (nav rows, sub-rows). Now each page entry in the
registry includes a layout identity (e.g. "sx-section:Testing") and
try-client-route falls through to server when layout changes, so OOB
header updates are applied correctly.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>