ci: add issue triage and stale management workflows

Add two GitHub Actions workflows for issue lifecycle management:

- needs-triage.yml: automatically labels new human-created issues
  with "needs-triage" (excludes bot accounts)
- stale.yml: marks inactive issues/PRs as stale after 60 days and
  auto-closes after 14 more days ("priority: high" is exempt)

Author: konokenj

.github/workflows/needs-triage.yml

@@ -0,0 +1,22 @@
+name: Add needs-triage label
+on:
+  issues:
+    types: [opened]
+
+permissions:
+  issues: write
+
+jobs:
+  add-label:
+    if: ${{ !endsWith(github.event.issue.user.login, '[bot]') }}
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/github-script@v7
+        with:
+          script: |
+            await github.rest.issues.addLabels({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              labels: ['needs-triage']
+            });

.github/workflows/stale.yml

@@ -0,0 +1,27 @@
+name: Close stale issues and PRs
+on:
+  schedule:
+    - cron: '0 0 * * *'
+
+permissions:
+  issues: write
+  pull-requests: write
+
+jobs:
+  stale:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/stale@v9
+        with:
+          days-before-stale: 60
+          days-before-close: 14
+          stale-issue-label: stale
+          stale-pr-label: stale
+          stale-issue-message: >
+            This issue has been automatically marked as stale because it has not had
+            recent activity. It will be closed if no further activity occurs within 14 days.
+          stale-pr-message: >
+            This PR has been automatically marked as stale because it has not had
+            recent activity. It will be closed if no further activity occurs within 14 days.
+          exempt-issue-labels: 'priority: high'
+          exempt-pr-labels: 'priority: high'