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>

src/components/OverviewPage.tsx

@@ -21,6 +21,7 @@ import {
   isEgressEnabled,
   isKubeVipService,
   isPodReady,
+  KUBE_VIP_NAMESPACE,
   phaseToStatus,
 } from '../api/k8s';
 import { useKubeVipContext } from '../api/KubeVipDataContext';
@@ -105,7 +106,7 @@ export default function OverviewPage() {
               {
                 name: 'Status',
                 value: (
-                  <StatusLabel status="error">No kube-vip pods found in kube-system</StatusLabel>
+                  <StatusLabel status="error">No kube-vip pods found in {KUBE_VIP_NAMESPACE}</StatusLabel>
                 ),
               },
               {