The upstream repo github.com/coreyhaines31/skills was renamed to
github.com/coreyhaines31/marketingskills, so the four curated
marketing-creative stubs (ad-creative, copywriting, marketing-psychology,
paywall-upgrade-cro) advertised a source URL that now 404s.
Update od.upstream and the body source/open links in all four SKILL.md
stubs, plus the matching entries in the seed script so re-seeding stays
consistent.