v0.4.0

What's Changed

• feat(docs): per-guide routes with full metadata, sitemap and robots by @lostmartian in #19
• feat(seo): technical foundation - structured data, OG cards, bundle diet, FAQ by @lostmartian in #20
• feat(site): agentdiff-style 404 report with typed terminal diff by @lostmartian in #21
• feat(blog): add MD-driven blog with hero, gradients and Goodhart post by @lostmartian in #22
• feat(cli): add 'record' subcommand — capture traces from any callable (E3) by @lostmartian in #23
• feat(governance): threshold-change flagging — the Goodhart guard (G6/G7) by @lostmartian in #24
• feat(governance): gate provenance in every report (G7) by @lostmartian in #25
• feat(governance): stale-baseline warning — surface baseline age (F7) by @lostmartian in #26
• docs: shell completion install instructions (E4) by @lostmartian in #27
• feat(website): site-wide redesign — new pages, editorial features page, tabbed surfaces by @lostmartian in #28
• chore(release): bump version to 0.4.0 by @lostmartian in #29

Full Changelog: v0.3.0...v0.4.0