Add Stale Action workflow for automatic closing of outdated issues

.github/workflows/stale.yml

@@ -0,0 +1,63 @@
+# Stale Action
+
+# This action automatically closes old issues to maintain repository cleanup
+# Reopen: Automatically closed issues must be manually reopened if still relevant,
+# and the 'stale' label removed to prevent reprocessing.
+
+name: 'stale'
+
+# If the permissions are restricted, the action could require more permission
+permissions:
+  issues: write
+
+# Cron runs the job at 13:00 German local time (CET/CEST)
+# GitHub Actions cron uses UTC, so the time is set to 11:00 UTC.
+on:
+  schedule:
+    - cron: 0 11 * * 1-5
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@v9
+        with:
+          close-issue-message: >
+            'This issue has been automatically closed due to age/inactivity. 
+            If still relevant with current software version, 
+            feel free to create a new issue with updated details. '
+          stale-issue-label: 'stale'
+
+          # Exemptions: Issues with milestones or labels 'ref/IP', 'ref/NC' are skipped.
+          exempt-issue-labels: 'ref/IP, ref/NC'
+
+          # Milestones on issues/PRs exempted from stale
+          exempt-milestones: true
+
+          # Days until issue gets 'stale' label (updated_at)
+          days-before-issue-stale: 1825
+
+          # Issues are closed immediately after being labeled stale
+          days-before-issue-close: 0
+
+          # Disables marking pull requests as stale and overrides
+          # the default (60 days)
+          days-before-pr-stale: -1
+
+          # Disables automatically closing pull requests after being marked stale
+          days-before-pr-close: -1
+
+          # Limits total API operations per run;
+          # since each issue needs 3 operations (label, message, close),
+          # max ~5 issues are processed per run.
+          # The action limits operations, not issues directly, so changing config
+          # (e.g., adding more labels or comments) affects
+          # how many issues can be handled in one run.
+          operations-per-run: 15
+          enable-statistics: true
+
+          # Processes oldest issues first
+          ascending: true
+
+          # Action only simulates the labeling and closing process, useful for testing
+          debug-only: true