feat: ACNA-4515 add pr-reviewer workflow

[chsrimanaswi]

Description

Adds an AI-powered PR reviewer workflow that automatically reviews pull requests using Claude via AWS Bedrock. Triggers on PR open/reopen/synchronize and on /review or /pr-reviewer comments by admins or maintainers.

Related Issue

https://jira.corp.adobe.com/browse/ACNA-4515

Motivation and Context

Reduces code review toil by providing automated first-pass reviews with inline suggestions. Part of a broader rollout across App Builder repos.

How Has This Been Tested?

Tested end-to-end in adobe/generator-aio-app — workflow triggers correctly on PR events and /review comments, posts inline suggestions and summary reviews via github-actions[bot].

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[github-actions]

🤖 PR Reviewer

The workflow is well-structured with a clear gate-check pattern separating permission validation from the actual review job. The use of environment variables to avoid injection and the fallback handling for the gh api call are good practices. One minor concern is pinning the reusable workflow to @main rather than a specific SHA or tag, which could introduce unexpected changes.

📝 1 suggestion(s) - Please review inline comments below.

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💡 How to re-trigger

Comment /review or /pr-reviewer on this PR

proposed changes not required