The page is now three things: what bench is, what installing costs, and
why to bother. The header nav is the way into the docs.
Removing them takes their CSS with them (.doors/.door* in the base sheet
and in all three breakpoints) and two tests that existed only for them —
the six-are-distinct check here and TheDoorsOpenOntoArticles in
test_site_pages. The hero-buttons test survives its class, renamed to say
what it now guards: the landing page's only links into the docs.
One test needed retargeting rather than deleting.
test_it_fails_before_anything_is_written removed /concepts/team-mode/
from the manifest to prove a dead internal link stops the build before
anything is written — but the link it relied on was a door. It now aims
at /guides/install/, which the hero button still hard-links.
Side effect worth having: the two reasons in "Why bench?" that nearly
repeated doors 03 and 04 no longer sit above them.