feat: add auto closing of issues / pull requests based on staleness (#1944)

<!-- This is an auto-generated description by cubic. -->

## Summary by cubic
Added GitHub workflows to automatically close stale issues and pull requests with unresolved merge conflicts older than 3 days.

- **Automation**
  - Closes open pull requests with merge conflicts after 3 days.
  - Closes issues immediately when marked as stale.

<!-- End of auto-generated description by cubic. -->



<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

* **Chores**
  * Introduced automated workflows to close old pull requests with unresolved merge conflicts and to close stale issues, helping keep the repository clean and up to date.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.github/workflows/close-conflicted-prs.yml

@@ -0,0 +1,50 @@
+name: Close Old Conflicted PRs
+
+on:
+  schedule:
+    - cron: "0 * * * *" 
+
+jobs:
+  close_conflicted_prs:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    steps:
+      - name: Close PRs with merge conflicts older than 3 days
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const prs = await github.rest.pulls.list({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              state: 'open'
+            });
+
+            const now = new Date();
+            for (const pr of prs.data) {
+              const details = await github.rest.pulls.get({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                pull_number: pr.number
+              });
+
+              if (details.data.mergeable === false || details.data.mergeable === null) {
+                const createdAt = new Date(pr.created_at);
+                const diffDays = (now - createdAt) / (1000 * 60 * 60 * 24);
+                if (diffDays > 3) {
+                  await github.rest.issues.createComment({
+                    owner: context.repo.owner,
+                    repo: context.repo.repo,
+                    issue_number: pr.number,
+                    body: "This PR has merge conflicts and has been open for more than 3 days. It will be automatically closed. Please resolve the conflicts and reopen the PR if you'd like to continue working on it."
+                  });
+                  
+                  await github.rest.pulls.update({
+                    owner: context.repo.owner,
+                    repo: context.repo.repo,
+                    pull_number: pr.number,
+                    state: 'closed'
+                  });
+                }
+              }
+            }

.github/workflows/close-stale-issues.yml

@@ -0,0 +1,21 @@
+name: Close Stale Issues
+
+on:
+  schedule:
+    - cron: "0 * * * *"
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    permissions:
+      issues: write
+      contents: read
+    steps:
+      - uses: actions/stale@v9
+        with:
+          days-before-stale: 3
+          days-before-close: 0
+          only-issues: true
+          stale-issue-label: "stale"
+          stale-issue-message: "This issue is stale (3+ days) and will be closed."
+          close-issue-message: "Closing stale issue."