Release v0.2.1 with minimal desktop assets

[oshtz]

What changed

• publish one universal macOS DMG and one Windows portable EXE
• retain only the universal macOS updater ZIP/feed and Windows portable checksum
• remove Windows installer/ZIP and all differential blockmaps
• force-rebuild better-sqlite3 before desktop packaging
• align release docs and version metadata at 0.2.1

Release shape

Five uploaded assets plus GitHub's two automatic source archives.

Validation

• 25 root tests + 8 API tests
• lint, desktop security, genome governance, production audit
• exact v0.2.1 tag contract and workflow YAML parse
• clean Windows portable-only build
• unpacked and portable two-launch persistence smoke
• minimal five-upload artifact verifier fixture

A signed universal macOS rehearsal will run after merge before tagging.