feat(releases): add changelog and release feeds

[bntvllnt]

Summary

• Promoted root CHANGELOG.md into the canonical Keep a Changelog source, added cliff.toml, and updated release docs/workflow so GitHub Release notes come from the changelog.
• Added /changelog, /releases, /rss.xml, /atom.xml, and /docs/changelog redirect, backed by a shared changelog/release parser with GitHub Releases fallback behavior.
• Added release discoverability across root feed alternates, sitemap, llms routes, header What's new menu, footer links, landing release strip, and package changelog notes.

Closes #260

Validation

• pnpm -F @vllnt/ui-registry exec eslint app/changelog/page.tsx app/releases/page.tsx app/docs/changelog/page.tsx app/rss.xml/route.ts app/atom.xml/route.ts app/layout.tsx app/llms.txt/route.ts app/llms-full.txt/route.ts app/sitemap.ts components/header/header.tsx components/footer/footer.tsx components/landing/landing.tsx lib/changelog.ts PASS
• pnpm -F @vllnt/ui-registry exec tsc --noEmit PASS
• pnpm -F @vllnt/ui lint PASS
• pnpm -F @vllnt/ui exec tsc --noEmit --project tsconfig.build.json PASS
• pnpm build PASS
• pnpm test:once PASS (216 files, 1215 tests)
• git diff --check PASS

Notes: pnpm build confirmed /changelog, /releases, /rss.xml, and /atom.xml in the Next route output. The build emits the existing worktree multiple-lockfile warning. Vitest emits existing dialog-description, duplicate-key, and jsdom navigation warnings while passing.

Design Deviations

None.

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Project	Deployment	Actions	Updated (UTC)
storybook	Ready	Preview, Comment	May 12, 2026 6:30pm
ui.vllnt.ai	Ready	Preview, Comment	May 12, 2026 6:30pm

[bntvllnt]

Blocking feed correctness issue: this emits Date.now() for any release without a date via buildRssDate(release.date). The root changelog currently includes [Unreleased], which entryToReleaseRecord turns into the 0.3.0 preview release with no date; the generated RSS from this PR shows that preview entry with the current request time as pubDate (and atom.xml has the same behavior for <updated>). That makes the feeds non-deterministic and tells feed readers an unpublished preview release is newly published on every rebuild/revalidation. Please either exclude undated/unreleased records from RSS/Atom, or give them a stable explicit timestamp before emitting feed items.

[bntvllnt]

PR review fallback (formal REQUEST_CHANGES unavailable because GitHub rejects requesting changes on my own PR):

Reviewed PR #337 at 3d18139.

Blocking finding:

• apps/registry/app/rss.xml/route.ts:39 — RSS/Atom feed items use current request time for undated release records. The current root CHANGELOG.md has [Unreleased], which becomes the 0.3.0 preview release with no date; generated RSS shows that preview item with a current pubDate, and Atom shows the same via updated. This makes the release feeds non-deterministic and advertises unpublished preview notes as newly published on every rebuild/revalidation. I left a line comment: feat(releases): add changelog and release feeds #337 (comment)

Validation evidence:

• git diff --check origin/main...HEAD: PASS
• pnpm -F @vllnt/ui-registry exec tsc --noEmit: PASS
• changelog/release helper smoke: 13 entries, 14 releases, first v0.3.0 with firstDate null
• RSS/Atom route smoke: HTTP 200, expected content-types, XML parses
• Evidence files: /tmp/pr337-review/final-validation.txt, /tmp/pr337-review/rss.xml, /tmp/pr337-review/atom.xml