feat: add per-namespace detail pages with dynamic sidebar sub-items

Add drill-down namespace views under the Polaris sidebar entry. Each
namespace gets a sidebar sub-item registered dynamically from audit data,
linking to /polaris/:namespace with a score summary and per-resource table.

Introduces a shared PolarisDataContext so the sidebar registrar and view
components share a single data fetch. Also updates the Artifact Hub
repository ID.

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

src/api/PolarisDataContext.tsx

@@ -0,0 +1,27 @@
+import React from 'react';
+import { AuditData, getRefreshInterval, usePolarisData } from './polaris';
+
+interface PolarisDataContextValue {
+  data: AuditData | null;
+  loading: boolean;
+  error: string | null;
+}
+
+const PolarisDataContext = React.createContext<PolarisDataContextValue | null>(null);
+
+export function PolarisDataProvider(props: { children: React.ReactNode }) {
+  const interval = getRefreshInterval();
+  const state = usePolarisData(interval);
+
+  return (
+    <PolarisDataContext.Provider value={state}>{props.children}</PolarisDataContext.Provider>
+  );
+}
+
+export function usePolarisDataContext(): PolarisDataContextValue {
+  const ctx = React.useContext(PolarisDataContext);
+  if (ctx === null) {
+    throw new Error('usePolarisDataContext must be used within a PolarisDataProvider');
+  }
+  return ctx;
+}