Adds a diagnostic step before E2E tests that:
- Logs the expected plugin version from package.json
- Verifies Headlamp is reachable (fails fast if not)
- Attempts to list installed plugins for debugging
This surfaces version mismatches and connectivity issues immediately
instead of requiring analysis of cryptic test timeout failures.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>