ci: add org-wide stale issue/PR workflow

[rubambiza]

Summary

• Add thin caller for the org-wide reusable stale workflow from kagenti/.github
• Marks issues and PRs as stale after 60 days of inactivity, closes after 14 more days

Test plan

• Trigger manually via workflow_dispatch and confirm it runs successfully

[huang195]

Clean, minimal thin-caller PR for the org-wide stale workflow. All 11 CI checks passing, DCO signed, proper Assisted-By attribution.

One concern: the reusable workflow is pinned to @main rather than a SHA — upstream changes to kagenti/.github take effect without explicit opt-in from this repo. This is common for org-internal workflows and may be intentional, but worth confirming as a deliberate choice.

Areas reviewed: CI/GitHub Actions, Security
Commits: 1 commit, signed-off: yes
CI status: all passing

[huang195]

suggestion: The reusable workflow is pinned to @main. This means any change to the org workflow takes effect immediately in this repo without review here. Consider pinning to a specific SHA for supply-chain safety, or confirm this is an intentional choice for org-internal workflows.

[rubambiza]

Good call flagging this. Using @main is an intentional choice for org-internal reusable workflows in kagenti -- we want upstream improvements (label changes, timing tweaks) to propagate automatically without requiring PRs to every consuming repo. This is the same pattern used by self-assign.yml across the org.

Added an inline comment in 6f4ae67 to make this explicit.

[huang195]

praise: Minimal permissions scoped to exactly what's needed (issues: write, pull-requests: write). Clean thin-caller pattern with good header comment and reference link.

[rubambiza]

Thanks!

[huang195]

Clean thin-caller PR for the org-wide stale workflow. Properly scoped permissions, DCO signed, Assisted-By attribution correct. The @main pinning concern from the prior review has been addressed with an inline comment in the second commit — intentional org-internal propagation pattern matching self-assign.yml across the org. All 11 CI checks passing.

Areas reviewed: CI/GitHub Actions, Security
Commits: 2 commits, all signed-off: yes
CI status: all passing