ci: add stale issue and PR cleanup workflow

.github/workflows/stale.yml

@@ -0,0 +1,45 @@
+name: Stale Issue/PR Cleanup
+
+on:
+  schedule:
+    - cron: "30 1 * * *"
+  workflow_dispatch:
+
+permissions:
+  issues: write
+  pull-requests: write
+
+jobs:
+  stale:
+    name: Mark stale issues and pull requests
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Run stale action
+        uses: actions/stale@v9
+        with:
+          stale-issue-label: stale
+          stale-pr-label: stale
+
+          days-before-issue-stale: 60
+          days-before-issue-close: 14
+          days-before-pr-stale: 30
+          days-before-pr-close: -1
+
+          exempt-issue-labels: pinned,security
+          exempt-pr-labels: pinned,security
+
+          remove-stale-when-updated: true
+
+          stale-issue-message: >
+            This issue has been automatically marked as stale because it has not
+            had recent activity for 60 days. It will be closed in 14 days if no
+            further activity occurs. To keep it open, please comment or remove
+            the stale label.
+          stale-pr-message: >
+            This pull request has been automatically marked as stale because it
+            has not had recent activity for 30 days. To keep it active, please
+            comment or remove the stale label.
+          close-issue-message: >
+            This issue was closed because it remained stale for 14 days with no
+            further activity.