fix: skipped display, namespace link crash, overview redesign

- Fix skipped count showing empty by rendering as plain text instead
  of StatusLabel with empty status (which renders near-invisible)
- Fix namespace link crash by using Router.createRouteURL to generate
  cluster-prefixed URLs with react-router-dom Link, instead of
  Headlamp's Link component which crashes on plugin-registered routes
- Redesign overview page with PercentageCircle score chart and
  PercentageBar check distribution for a better visual experience

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/NamespaceDetailView.tsx

@@ -120,7 +120,7 @@ export default function NamespaceDetailView() {
             },
             {
               name: 'Skipped',
-              value: <StatusLabel status="">{counts.skipped}</StatusLabel>,
+              value: String(counts.skipped),
             },
           ]}
         />