chore: Adding missing permissions to stale workflow

[devin-ai-integration]

Note

Low Risk
Low risk GitHub Actions config change that only adjusts workflow permissions for issue/PR management.

Overview
Ensures the stale.yml scheduled workflow can manage repository items by explicitly granting issues: write and pull-requests: write permissions.

Also normalizes YAML quoting for the workflow name and cron schedule.

^{Reviewed by Cursor Bugbot for commit c5d77ec. Bugbot is set up for automated code reviews on this repo. Configure here.}