ci: close inactive pull requests automatically

Mark pull requests stale after 30 inactive days and close them seven days later. Clear the stale state when new activity arrives so active contributions remain open.

.github/workflows/stale.yml

@@ -1,4 +1,4 @@
-name: Stale Issues
+name: Stale Issues and Pull Requests
 
 on:
   schedule:
@@ -8,11 +8,11 @@ on:
 permissions:
   actions: write
   issues: write
-  pull-requests: read
+  pull-requests: write
 
 jobs:
   stale:
-    name: Mark and Close Stale Issues
+    name: Mark and Close Stale Issues and Pull Requests
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
@@ -21,11 +21,11 @@ jobs:
           operations-per-run: 1000
           days-before-issue-stale: 60
           days-before-issue-close: 14
-          days-before-pr-stale: -1
-          days-before-pr-close: -1
+          days-before-pr-stale: 30
+          days-before-pr-close: 7
           stale-issue-label: stale
           stale-pr-label: stale
-          remove-pr-stale-when-updated: false
+          remove-pr-stale-when-updated: true
           exempt-issue-labels: "pinned,security,discussion"
           stale-issue-message: >
             This issue has been inactive for 60 days. It will be closed in 14 days
@@ -33,3 +33,8 @@ jobs:
             comment or update the issue.
           close-issue-message: >
             Closing due to inactivity. Feel free to reopen if this is still relevant.
+          stale-pr-message: >
+            This pull request has been inactive for 30 days. It will be closed in 7 days
+            unless there is new activity.
+          close-pr-message: >
+            Closing due to inactivity. Feel free to reopen when this is ready to continue.