repo-add --new skips updating entries that are already in the db, so when
the omarchy-* packages are rebuilt in place (new content, same filename,
because pkgver is constant) the persistent cache's offline.db.tar.gz
kept the OLD size/checksum entries. Pacman then read the stale db size
and rejected the new file with 'Exceeded the maximum allowed file size'.
Delete the db files and let repo-add regenerate them fresh — slower but
deterministic, and 'offline.db.tar.gz' is small to rebuild even for the
full ~600 package set.