ci: resolve PR number from head repo/branch for fork PRs

[btea]

Description

The "Leave a comment" workflow fails because thollander/actions-comment-pull-request runs on the deprecated Node 20 runtime [1], and the upstream PR upgrading it to Node 24 [2] has been open without activity since March 2026.

Replace the action with a local composite action built on actions/github-script. The marker format is kept so existing
tagged comments are updated instead of duplicated.

[1] https://github.com/nodejs/doc-kit/actions/runs/31868656146/job/94973630400
[2] thollander/actions-comment-pull-request#449

Validation

Related Issues

Check List

• I have read the Contributing Guidelines and made commit messages that follow the guideline.
• I have run node --run test and all tests passed.
• I have check code formatting with node --run format:check & node --run lint.
• I've covered new added functionality with unit tests if necessary.

[vercel]

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Project	Deployment	Actions	Updated (UTC)
api-docs-tooling	Ready	Preview	Aug 15, 2026 3:33pm

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.46%. Comparing base (15b3f3e) to head (5cfcc33).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1041      +/-   ##
==========================================
+ Coverage   89.37%   89.46%   +0.09%     
==========================================
  Files         203      203              
  Lines       18986    19039      +53     
  Branches     1769     1782      +13     
==========================================
+ Hits        16968    17033      +65     
+ Misses       2011     1999      -12     
  Partials        7        7              

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[MattIPv4]

I don't think Node.js 20/24 has anything to do with that failure -- the workflow was triggered from a commit on main, and so github.event.workflow_run.pull_requests[0].number used as the input will not be populated.

[btea]

You're right, I didn't address the error; I simply removed the warning message about the Node version. I've rewritten the logic, but it doesn't seem to be directly verifiable in this PR.

[avivkeller]

I'm also wary to replace something that works, if it ain't broke don't fix it... why do we need our own logic when an external action works fine

[btea]

The local logic was added to resolve a Node.js version compatibility warning. The upstream action hasn't been updated in a long time, suggesting the author is no longer managing it. If you believe this warning can be ignored, I can revert the code and continue using the upstream action.

[MattIPv4]

👍 Yes, no need to introduce additional maintenance burden by rolling our own action, the upstream works w/ Node.js 24.

[MattIPv4]

Can we follow the same pattern as in https://github.com/nodejs/nodejs.org/blob/main/.github/workflows/leave-comment.yml, please, so we have consistent implementations?

[btea]

It turns out there's a well-established logic to refer to; thank you for pointing that out.

[MattIPv4]

@btea could I ask if you're using AI for your contributions and/or your comments?