fix: extract cluster from URL path in AppBar badge (useCluster returns null outside cluster routes)

useCluster() returns null when called from AppBar context because the
component renders outside the cluster route hierarchy. Parse the cluster
name from location.pathname instead, with useCluster() as fallback.

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

src/components/AppBarScoreBadge.tsx

@@ -1,7 +1,7 @@
 import { K8s } from '@kinvolk/headlamp-plugin/lib';
 import { useTheme } from '@mui/material/styles';
 import React from 'react';
-import { useHistory } from 'react-router-dom';
+import { useHistory, useLocation } from 'react-router-dom';
 import { computeScore, countResults } from '../api/polaris';
 import { usePolarisDataContext } from '../api/PolarisDataContext';
 
@@ -13,7 +13,13 @@ export default function AppBarScoreBadge() {
   const theme = useTheme();
   const { data, loading } = usePolarisDataContext();
   const history = useHistory();
-  const cluster = K8s.useCluster();
+  const location = useLocation();
+  const clusterFromHook = K8s.useCluster();
+
+  // useCluster() returns null in AppBar context (outside cluster routes),
+  // so extract cluster from the current URL path as primary source.
+  const clusterMatch = location.pathname.match(/^\/c\/([^/]+)/);
+  const cluster = clusterMatch ? clusterMatch[1] : clusterFromHook;
 
   if (loading || !data) {
     return null; // Graceful degradation when Polaris unavailable