fix(kube-vip): revert docs namespace to kube-system (PRI-562)

Revert CLAUDE.md, README.md, and SECURITY.md namespace references from
'headlamp' back to 'kube-system' to match src/api/k8s.ts KUBE_VIP_NAMESPACE.

The source code uses 'kube-system' as the namespace constant; docs must
match code to avoid misleading users.

Also fixes hardcoded namespace string in OverviewPage.tsx to use
KUBE_VIP_NAMESPACE constant instead of literal 'kube-system'.

Option A per PRI-562 QA guidance.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

SECURITY.md

@@ -12,10 +12,10 @@ This plugin is **read-only**. It does not perform any write operations against t
 
 - Services (type: LoadBalancer)
 - Nodes
-- Pods in `headlamp`
-- DaemonSets in `headlamp`
-- Leases in `headlamp`
-- ConfigMaps in `headlamp`
+- Pods in `kube-system`
+- DaemonSets in `kube-system`
+- Leases in `kube-system`
+- ConfigMaps in `kube-system`
 
 All data is fetched through Headlamp's built-in API proxy, which respects the user's existing RBAC permissions.