An empty min_release_age string now maps to unparseable rather than absent,
so "min_release_age": "" fails validation instead of silently running
with a zero-second quarantine. The end-to-end fixtures extend the
checked-in pkgver (.90/.91) so the test keeps working at any future mise
version. A Tests workflow runs bin/sync-upstream self-test and
bin/omarchy-pkgs self-test on every PR in the Arch container, making the
proof machine-checked instead of author-supplied. The README package
metadata field list documents upstream and min_release_age.
