feat: query Polaris dashboard API instead of ConfigMap

The plugin now fetches audit data from the Polaris dashboard service
via the Kubernetes service proxy instead of reading from a ConfigMap.
This works with the standard Polaris dashboard deployment without
requiring additional configuration.

- Replace ConfigMap.useGet with ApiProxy.request to /results.json
- Compute score from result counts (pass/total) since the API
  response doesn't include a pre-computed score
- Update error messages for service proxy context
- Update CLAUDE.md to reflect new data source

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

src/components/PolarisView.tsx

@@ -2,6 +2,7 @@ import { Loader, SectionBox, SectionHeader } from '@kinvolk/headlamp-plugin/lib/
 import React from 'react';
 import {
   AuditData,
+  computeScore,
   countResults,
   getRefreshInterval,
   ResultCounts,
@@ -69,10 +70,11 @@ function ScoreBadge(props: { score: number }) {
 }
 
 function OverviewSection(props: { data: AuditData; counts: ResultCounts }) {
+  const score = computeScore(props.counts);
   return (
     <>
       <SectionBox title="Score">
-        <ScoreBadge score={props.data.Score} />
+        <ScoreBadge score={score} />
       </SectionBox>
       <SectionBox title="Check Summary">
         <div