Runs the real static/dash-layout.js under node (CI's job container has it;
the checkout action runs on it) over a saved layout with 60 random sets of
content heights at 12-24 columns. Expected to fail against today's pack(),
which places by content height: pushed alone so CI shows the guard can fail
before the fix lands.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
