Update draft release PR comment when release is published

[joshjohanning]

Problem

When create_release_as_draft: true and draft_release_pr_reminder: true, the action posts a comment on the merged PR with a link to the draft release. However, the draft release URL breaks (404s) after the release is published since draft releases use a different URL format. The comment should be updated to reflect the published release with a working link.

Next Steps

• Review the release notes
• Publish the release to make it permanent

Solution (implemented in PR #98)

Option 1: Single action, event-type branching — the action checks context.eventName and branches behavior:

• On push → normal publish flow (existing behavior)
• On release: [published] → find and update the draft comment, then return early

on:
  push:
    branches: [main]
  release:
    types: [published]

Example: Before (draft)

## 📦 Draft Release Created

A draft release **v3.1.1** has been created for this PR.

🔗 **[View Draft Release](https://github.com/.../releases/tag/untagged-...)**

### Next Steps
- [ ] Review the release notes
- [ ] Publish the release to make it permanent

Example: After (published)

## ✅ Release Published

Release **v3.1.1** has been published!

🔗 **[View Published Release](https://github.com/.../releases/tag/v3.1.1)**

### Next Steps
- [x] Review the release notes
- [x] Publish the release to make it permanent

Implementation Notes

• Version-specific HTML marker (<!-- publish-github-action-draft:vX.Y.Z -->) for reliable comment matching
• Legacy fallback for comments without marker (heading + version match)
• Author filtering to only update our own comments
• Idempotency: skips if comment already shows published state
• Predictable tag URL (draft untagged-... URLs 404 after publishing)
• Uses retryWithBackoff on all API calls
• 13 tests covering all paths

[joshjohanning]

Note: Can use a dynamic run-name to distinguish runs in the Actions UI:

run-name: >-
  ${{
    github.event_name == 'release' && format('Update PR comment for {0}', github.event.release.tag_name) ||
    format('Publish {0}', github.sha)
  }}

• Push events → "Publish abc123..."
• Release events → "Update PR comment for v3.1.1"

(package.json version isn't available at the run-name level — only GitHub contexts — so push events use the commit SHA.)