Add GitHub workflow to lock stale issues

- Locks issues closed for 7+ days without activity
- Runs daily at 7am Pacific (2pm UTC)
- Includes manual workflow dispatch trigger
- Posts helpful comment before locking with guidance for new issues

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.github/workflows/lock-closed-issues.yml

@@ -0,0 +1,31 @@
+name: 'Lock Stale Issues'
+
+on:
+  schedule:
+    # 7am Pacific = 2pm UTC (3pm UTC during DST)
+    - cron: '0 14 * * *'
+  workflow_dispatch:
+
+permissions:
+  issues: write
+
+concurrency:
+  group: lock-threads
+
+jobs:
+  lock-threads:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: dessant/lock-threads@1bf7ec25051fe7c00bdd17e6a7cf3d7bfb7dc771  # v5.0.1
+        with:
+          issue-inactive-days: '7'
+          pr-inactive-days: '36500'  # ~100 years (effectively disabled)
+          discussion-inactive-days: '36500'  # ~100 years (effectively disabled)
+          process-only: 'issues'
+          issue-lock-reason: 'resolved'
+          issue-comment: >
+            This issue has been automatically locked since it was
+            closed and has not had any activity for 7 days.
+            
+            If you're experiencing a similar issue, please file a new issue
+            and reference this one if it's relevant: #${{ github.event.issue.number }}