Home page now shows one clickable summary card per entity type
(Networks, Hosts, Applications). Each card displays the total count
fetched from the database via a single get_summary() server function,
then navigates to the corresponding page on click.
Counts are pre-rendered server-side via <Suspense> so the page is
useful even before the WASM bundle loads.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
