closed-source v0.3.1

What's Changed

• docs(release): v0.3.0 is live: its changelog on the site, CI the same on a pull request and on main by @h0ffmann in #48
• docs(notes): four notes from thinking out loud to friend3, with sources and easy pt-BR versions by @h0ffmann in #49
• docs: notes (the first Scala, Marcus Baffa, Pirsig), the essay "New vs. better, 2026", the essay-montaigne skill by @h0ffmann in #50
• docs: peer review (a note and a one-page essay), Kubrick as thinker 39, PRINTING.md and the print skill by @h0ffmann in #51
• docs: picasso and determinism: a note with a study, the essay "picasso, and the long run" by @h0ffmann in #52
• ci: pace the link check, so github.com's 500s do not fail it by @h0ffmann in #53
• docs: nashkell's open book has a DOI, 10.5281/zenodo.23356739 by @h0ffmann in #54
• notes: a TV audience is a competition, and I think in game theory by @h0ffmann in #56
• ai-memory as the long-term memory of closed-source: change proposal and readiness list by @h0ffmann in #55
• ci: perma-doi, a daily release at 18:00 in Brasília, minted by Zenodo by @h0ffmann in #59
• essay temporary retirement from website by @h0ffmann in #58
• notes: Art is dead. The age of copy. (featured, with Gregory Wolfe's Beauty essays) by @h0ffmann in #57

Full Changelog: v0.3.0...v0.3.1