ci: implement stale issue and pr policy (issue #119)

[OpadijoIdris]

Implement Stale Issue and PR Policy (#119)

Summary

This PR manages the project backlog by adding a GitHub Action workflow that automatically identifies, warns, and closes stale issues and pull requests after a prolonged period of inactivity (60 days). This helps keep the repository clean and ensures active issues are properly prioritized.

Related Issue

Closes #119

Type of Change

• Feature
• Bug fix
• Refactor
• Documentation

Changes Made

• Created .github/workflows/stale.yml utilizing the actions/stale@v9 action.
• Set the staleness threshold to 60 days of inactivity before an item is marked as stale.
• Configured warning messages to inform contributors they have 7 days to engage with the issue/PR before it is automatically closed.
• Configured final messages to be appended upon closure.
• Implemented specific exemptions for issues (e.g., bug, security) and PRs (e.g., dependencies, wip) to ensure heavily tracked items are not incorrectly closed.

Validation

• cargo fmt --all (if contract changed)
• npm run lint in frontend (if frontend changed)
• Manual verification completed

Screenshots (if UI changes)

N/A

Checklist

• Scope is focused and avoids unrelated changes
• Commit messages are clear
• Documentation updated when needed
• ETA was provided when requesting assignment for the linked issue

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@OpadijoIdris Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

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[ayomideadeniran]

Pr under review.