Adds stale PR and issue labeling workflow

[zktaiga]

Implements a GitHub Actions workflow that automatically labels pull requests and issues as stale after 60 days of inactivity.
It will post a message and apply a 'stale' label.
The workflow runs daily and can be manually triggered.

[Copilot]

Pull Request Overview

Implements an automated stale-labeling workflow for pull requests and issues after 60 days of inactivity.

• Adds a GitHub Actions workflow triggered daily (and manually)
• Uses actions/stale@v9.1.0 to apply a stale label and post custom messages
• Sets days-before-close to -1 to disable automatic closing

Comments suppressed due to low confidence (2)

.github/workflows/stale.yml:14

• [nitpick] Add a concurrency group to the workflow to prevent overlapping runs and reduce potential rate-limit issues, e.g.:

concurrency:
  group: 'stale-workflow'
  cancel-in-progress: false

jobs:

.github/workflows/stale.yml:18

• [nitpick] Consider adding an exempt-labels input (e.g., pinned, security) so critical issues or PRs aren’t marked stale unintentionally.

      - uses: actions/stale@v9.1.0