The density data is fetched only on tablet/desktop (sm:+ breakpoint) and
when ?view=calendar is not set — mobile users and the future calendar view
(#386) skip the request entirely. Lives in +page.ts (client-side) so the
matchMedia gate can run in the browser; +page.server.ts continues to handle
the document search.
Non-ok responses and network failures degrade to an empty bucket list
rather than throwing, so the document list keeps rendering.
5 unit tests cover the gating + graceful degradation paths.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
