db.Skills() satisfies skill.SkillStore over SQLite, same JSON-blob + indexed
columns pattern. Versions live in their own table (each SkillVersion embeds a
full Skill snapshot as JSON), ordered newest-first by an append seq.
Test: round-trip (Tools, ExposeAsChatbotTool), visibility listing
(public/shared/private with SharedWith filtered in Go), chatbot-exposed,
newest-first versions + GetVersionByID, scheduled-due query + MarkScheduledRun.
contrib/store now covers budget + persona + skill; audit store next.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
