fix: add missing permissions to GitHub Actions workflows

- Add issues, pull-requests, and checks write permissions to test.yml
- Add statuses write permission to benchmark-pr.yml
- Fixes "Resource not accessible by integration" errors in CI/CD

These permissions allow workflows to create PR comments and commit statuses.

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

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

.github/workflows/benchmark-pr.yml

@@ -11,6 +11,7 @@ on:
 permissions:
   pull-requests: write
   contents: read
+  statuses: write
 
 jobs:
   benchmark-comparison: