feat(ci): add release-notes version drift check (Stage 0)

[jstirnaman]

Summary

Closes #

Adds a PR check that guards against version drift: when a product's release
notes gain a new ## vX.Y.Z heading but data/products.yml is not bumped. That
version feeds the {{< latest-patch >}} shortcode, which builds every
dl.influxdata.com download URL and the versions in install/code examples — so a
missed bump silently points the docs at the previous release, with no signal.
(Verified against the live repo: the v3.10.3 release commit 848a6ba added notes
only, with no safeguard.)

What this adds (Stage 0):

• .ci/scripts/check-release-notes-version.js (+ .test.js) — compares each
  product's newest release-notes heading to data/products.yml, handling both the
  scalar latest_patch and the map latest_patches.<version> shapes. Non-blocking
  reminder; every product is checked and reported — Telegraf included (it
  normally reports ✅ because its internal automation keeps the value in sync, and a
  mismatch would flag a regression there).
• .github/workflows/pr-release-check.yml — posts the reminder as a sticky PR
  comment (change detection via git diff, not the flaky Files API), plus a
  release-readiness gate that, only on a real version bump, blocks merge if the
  new version's download artifacts aren't published yet. Override with the
  release:artifacts-pending label when docs are intentionally staged ahead.
• .github/workflows/pr-link-check.yml — now also checks the download/install
  pages when data/products.yml changes, closing the gap where a version-only PR
  never re-checked those URLs.
• .agents/skills/docs-testing/SKILL.md — documents both in the CI table.
• docs/exec-plans/2026-07-21-release-notes-version-drift-check.md — decision
  record covering Stage 0 and the Stage 1–4 roadmap toward source-driven docs that
  prevent drift entirely (the Telegraf model, now feasible for Core/Enterprise/Cloud
  since they share one source repo).

Also reminds authors they can badge new-feature pages with the existing
frontmatter mechanism (metadata: / updated_in: / introduced:) — the same
badge the v3.10.3 feature pages did not use.

Opened as draft. This is Stage 0 of a staged effort; Stages 1–4 (auto-bump,
release-triggered PRs, single-source-of-truth, generated reference docs) are
documented in the exec-plan and are out of scope here.

Verification

node .ci/scripts/check-release-notes-version.test.js   # 8/8 pass
node .ci/scripts/check-release-notes-version.js         # all products ✅ in sync
yarn build:agent:instructions && yarn validate:agent-instructions  # clean

Both workflows parse as valid YAML; all third-party actions are pinned by commit
SHA per repo policy.

Checklist

• Signed the InfluxData CLA (if necessary)
• Rebased/mergeable
• Local build passes (npx hugo --quiet)

🤖 Generated with Claude Code

---

Generated by Claude Code

[github-actions]

Release version check

No release-notes pages with a tracked version changed in this PR.

💡 Badge new features with the version

Documenting a new feature? Add a version badge in the page frontmatter — the
same mechanism used elsewhere in the docs:

• metadata: [InfluxDB 3 Core v3.11+] — badge list under the page title
• updated_in: v3.11 — an "Updated in v3.11" badge
• introduced: v3.11 — a "‹Product› v3.11+" badge
• menu.params.state: new — a "NEW" pill on the sidebar nav item

For inline version text, use {{< latest-patch >}} / {{< current-version >}},
which read the value from data/products.yml so it stays correct automatically.

[Copilot]

Pull request overview

Adds CI safeguards for release-note and product-version drift, plus artifact-readiness checks.

Changes:

• Adds release-version comparison logic and tests.
• Adds release artifact and expanded link-check workflows.
• Documents testing and future automation plans.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
.ci/scripts/check-release-notes-version.js	Implements version drift detection.
.ci/scripts/check-release-notes-version.test.js	Tests comparison and mapping logic.
.github/workflows/pr-release-check.yml	Adds reminders and artifact gating.
.github/workflows/pr-link-check.yml	Expands checks after product-version changes.
.agents/skills/docs-testing/SKILL.md	Documents the new CI checks.
docs/exec-plans/2026-07-21-release-notes-version-drift-check.md	Records decisions and roadmap.