ci: auto-manage stale pull requests and issues (#155)

The PR queue reached 53 open, with the oldest sitting untouched for eight
months. None of that was caused by bad submissions - nothing ever closed
anything, so contributors got no answer and the queue stopped being
reviewable.

60 days to stale, 21 more to close. Deliberately generous: contributors
here are volunteers adding a row to a catalog, and the goal is to close
what is genuinely abandoned rather than to rush anyone. Any activity
removes the label, so a contributor can rescue their own PR without
needing me.

operations-per-run is capped at 30 with ascending order so the first run
works through the oldest items in batches instead of mass-closing the
backlog in one pass. Anything labelled pinned, security, in progress or
awaiting-maintainer is exempt.

Signed-off-by: ashishpatel26 <3095771+ashishpatel26@users.noreply.github.com>
Co-authored-by: ashishpatel26 <3095771+ashishpatel26@users.noreply.github.com>

.github/workflows/stale.yml

@@ -0,0 +1,66 @@
+name: Stale
+
+on:
+  schedule:
+    - cron: '0 3 * * 1'  # Mondays, 03:00 UTC
+  workflow_dispatch:
+
+permissions:
+  issues: write
+  pull-requests: write
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@v9
+        with:
+          # Deliberately generous. Contributors here are volunteers adding a row
+          # to a catalog, not staff. The goal is to close what has genuinely been
+          # abandoned, not to rush anyone.
+          days-before-stale: 60
+          days-before-close: 21
+
+          stale-pr-message: >
+            This PR has had no activity for 60 days, so I'm marking it stale.
+
+
+            If you're still interested, just push a commit or leave a comment and
+            I'll take the label off. Rebasing onto current `main` is usually all
+            it needs — this README changes often and older branches stop merging
+            cleanly.
+
+
+            If I don't hear anything in 21 days it'll close automatically. That's
+            not a rejection and you can reopen it any time.
+
+          close-pr-message: >
+            Closing this after 81 days without activity.
+
+
+            No hard feelings and nothing personal — I'd rather keep the queue
+            honest than leave PRs sitting open indefinitely with no answer.
+            Reopen it whenever you like, or open a fresh one against current
+            `main`.
+
+          stale-issue-message: >
+            This issue has had no activity for 60 days, so I'm marking it stale.
+            Comment if it's still relevant and I'll keep it open.
+
+          close-issue-message: >
+            Closing after 81 days without activity. Reopen if it's still an issue.
+
+          stale-pr-label: stale
+          stale-issue-label: stale
+
+          # Anything I've explicitly triaged is never auto-closed.
+          exempt-pr-labels: 'pinned,security,in progress,awaiting-maintainer'
+          exempt-issue-labels: 'pinned,security,in progress,awaiting-maintainer'
+
+          # Removing the label on new activity is the point - it lets a
+          # contributor rescue their own PR without needing me.
+          remove-stale-when-updated: true
+
+          # Small batches so a first run cannot mass-close the backlog.
+          operations-per-run: 30
+          ascending: true