feat: GitHub App workflow to mark issues/comments as unread for maintainers

[RAWx18]

Feature Summary

Add a GitHub App–based workflow that helps maintainers track new issue activity. If a non-maintainer creates an issue or comments on one, it should be marked as unread until a maintainer responds. This logic should live in the repository’s .github configuration, not inside the GitMesh application codebase.

Use Case / Problem

• Non-maintainer creates an issue or comments on an existing issue
• Maintainer checks issue activity

Suggested Solution

Issues/comments from non-maintainers are marked as unread until a maintainer replies. Currently, No unread tracking exists; maintainers can miss new issues or comments.

Alternatives Considered

No response

Additional Context

• Must be implemented using .github workflows / GitHub App configuration, not inside GitMesh core code.
• Should reliably distinguish maintainers vs non-maintainers.
• “Unread” state clears only after a maintainer response, not just a view.
• Should follow classic open-source issue triage patterns (similar to large OSS projects).
• Can leverage labels, issue state, comments, or metadata managed via GitHub automation.

[RAWx18]

I am no longer actively maintaining this project and @Ronit-Raj9 and @Parvm1102 are the current active maintainers who will take this forward.