Revert namespace references from headlamp back to kube-system in docs since
kube-vip workload runs in kube-system namespace (not headlamp which is the
Headlamp plugin install namespace).
Changes:
- CLAUDE.md: revert data sources and key constants namespace
- README.md: revert requirements line and troubleshooting table
- SECURITY.md: revert plugin scope namespaces
- OverviewPage.tsx: use KUBE_VIP_NAMESPACE constant instead of hardcoded string
Fixes PRI-562