Release PR Auto-Release Fix

Goal

Fix the follow-up release PR behavior after PR #4957:

• Do not add the managed Auto release checkbox to PRs whose title contains Version packages.
• Unblock generated release PR auto-merge by letting the required CI check run instead of skipping it.
• Remove the stray checkbox from PR #4961.

Findings

• PR #4961 title is [Release] Version packages.
• PR #4961 has auto-merge enabled, but mergeStateStatus is BLOCKED.
• The active ruleset for main requires CI and Vercel.
• PR #4961 has Vercel success and CI skipped.
• .github/workflows/ci.yml skips pull requests whose title is exactly [Release] Version packages.
• .github/workflows/changeset-auto-release.yml currently manages any PR with a .changeset/*.md filename, including generated release PRs that delete changesets.
• bun test tooling/scripts/auto-release-pr.test.mjs failed before the helper export existed, then passed after adding the title guard helper.
• Editing PR #4961 before this workflow fix lands triggers the old Sync auto-release checkbox workflow, which re-adds the block because it still runs on [Release] Version packages.

Plan

1. [complete] Confirm the root cause with PR metadata and repo rulesets.
2. [complete] Add helper coverage for release PR title detection and block removal.
3. [complete] Skip checkbox management for Version packages PR titles.
4. [complete] Let CI run on release PR pull_request events.
5. [complete] Verify with targeted tests and repo checks.
6. [in_progress] Commit, push, open PR.
7. [pending] Clean up PR #4961 body after the workflow fix lands.

Verification

• bun test tooling/scripts/auto-release-pr.test.mjs failed before implementation, then passed after the helper/workflow fix.
• node --check tooling/scripts/auto-release-pr.mjs && node --check tooling/scripts/auto-release-pr.test.mjs passed.
• ruby -e 'require "yaml"; ...' .github/workflows/ci.yml .github/workflows/changeset-auto-release.yml passed.
• git diff --check passed.
• pnpm lint:fix passed with no fixes.
• pnpm check passed. Existing warning: apps/www/src/registry/ui/footnote-node.tsx hook dependency warning.