feat(ci): add PR welcome comment workflow

[Atliac]

Add a GitHub Actions workflow that automatically posts a guidance comment on newly opened pull requests with review instructions for contributors, reviewers, and maintainers.

[github-actions]

Welcome and Thank You! 👋

Thank you for opening this pull request!

⏳ Note on Review Times

The maintainer may not react immediately. This is expected and normal, as the project is maintained as time permits. Thank you for your patience!

🔗 For the PR Contributor

1. Link and Auto-Close Issues:

   If this PR fixes any existing issues, please make sure to include closing keywords (such as closes #123 or fixes #456) in your first PR message (the main description). This links the issues and automatically closes them when this PR is merged.

2. Invite Reviewers on Linked Issues:

   If this is a non-trivial PR, please leave a comment on the linked issues to invite others to review your changes. You can copy and paste the encouraging template below:

   Hey everyone! I have opened a PR (#5) to resolve this issue. I am inviting you to help test and review the PR!
   
   - **No write access is needed** to participate or leave a review.
   - **No deep understanding of the codebase is required**—you can simply verify if the changes fix the problem for you and do not introduce new issues.
   - **Everyone benefits from multiple reviews** because diverse testing and feedback ensure the fix is robust, does not break other features, and gives the maintainer the confidence to merge the changes quickly.
   
   If you have a moment to check it out and leave your feedback or approval, it would be greatly appreciated!
   

🔍 For Everyone (No Write Access Needed!)

Anyone can help review and approve this PR. Here is how you can participate:

1. Inspect for Malicious Code:

   Go to the "Files changed" tab, or check out the PR locally to inspect the changes:

   gh pr checkout 5
   git diff origin/main

   (Note: This step only requires checking for obvious safety/security issues, and does not require deep understanding of the codebase.)

2. Run the Project:

   Run the project against this PR locally to tell if issues are solved and new issues introduced.

3. Submit a Review:

   • If you find issues, submit a review or leave a comment with your feedback.
   • If everything looks correct, submit an Approve review (or leave a comment stating you approve) and briefly explain what you checked/tested.

🛠️ For the Maintainer

If this PR is reviewed and approved by two or more independent (standalone) reviewers, it will significantly speed up the merge progress.

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Automated message maintained by Atliac.

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Summary by CodeRabbit

• Chores
  • Added automated welcome comment on pull requests to provide contributors with guidance and helpful resources for the review process.

Walkthrough

A new GitHub Actions workflow (.github/workflows/pr-welcome.yml) is added. It triggers on PR opened and ready_for_review events, checks existing PR comments for a fixed signature string to avoid duplicates, and posts a Markdown guidance message via the GitHub REST API if no prior comment is found.

Changes

PR Welcome Comment Workflow

Layer / File(s)	Summary
Workflow triggers, permissions, and job definition .github/workflows/pr-welcome.yml	Declares the workflow name, event triggers (opened, ready_for_review), write permissions for pull-requests and issues, and the post-guidance job on ubuntu-latest.
Duplicate detection, comment body construction, and posting .github/workflows/pr-welcome.yml	Script reads context.issue.number, fetches existing comments and scans for a guidance signature to skip duplicates, constructs a multi-section Markdown comment body with the PR number, and calls github.rest.issues.createComment to post it.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'feat(ci): add PR welcome comment workflow' accurately describes the main change—adding a GitHub Actions workflow that posts welcome comments on pull requests.
Description check	✅ Passed	The description is directly related to the changeset, explaining that the workflow automatically posts guidance comments on newly opened pull requests with review instructions.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch pr-welcome

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_{Comment @coderabbitai help to get the list of available commands and usage tips.}