tests/__init__.py keeps a run offline, its scratch under tmp/ and its
installer cache its own, but only discover -s tests -t . imported it.
discover tests ran with RETROBIOS_OFFLINE unset, scratch on the /tmp
tmpfs and the user's real installer cache, the setting in which e2e
fixtures had written into the shared .cache/large. Every test module now
imports the package first, and a test fails on a module that does not.
test_verify_listing.py took its line with the previous commit.
Tables with a download link stack on phones, the browser check covers
the lookup, a hash typed in the search, breadcrumbs, previous and next
across tabs, glossary terms and the 404 hint. validate_site budgets the
Pagefind index pieces and takes the base path without mkdocs.yml. A
test holds the picker to install.narrow() on 180 selections.