feat: add CTA Assistant workflow for automated contributor agreement management (#247)

* feat: add CTA Assistant workflow for automated contributor agreement management

- Add GitHub Actions workflow to automate CTA signature collection
- Triggers on PR events and issue comments for signature requests
- Uses WalletConnect/actions/github/cta-assistant@master
- Includes required permissions for PR management and signature storage
- Follows standard CTA Assistant configuration pattern

Co-Authored-By: Ben Kremer <[email protected]>

* fix: pin CTA Assistant action to specific commit hash

- Use commit hash 7a3ca8b instead of @master for better version stability
- Addresses feedback from PR review

Co-Authored-By: Ben Kremer <[email protected]>

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: Ben Kremer <[email protected]>

Author: devin-ai-integration[bot]

.github/workflows/cta.yml

@@ -0,0 +1,21 @@
+name: "CTA Assistant"
+on:
+  issue_comment:
+    types: [created]
+  pull_request_target:
+    types: [opened, closed, synchronize]
+
+# Required permissions
+permissions:
+  actions: write
+  contents: write # can be 'read' if signatures are in remote repository
+  pull-requests: write
+  statuses: write
+
+jobs:
+  CTA:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: WalletConnect/actions/github/cta-assistant@7a3ca8b
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}