feat: add Playwright E2E smoke tests and fix empty namespace crash

Fix getNamespaces() to skip cluster-scoped resources (Namespace: "")
that caused Router.createRouteURL to throw TypeError on the Namespaces
page. Add Playwright E2E smoke tests with Authentik OIDC auth for CI
and K8s token fallback for local dev. Add Gitea Actions E2E workflow,
vitest unit test infrastructure, and test-utils fixtures.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/test-utils.tsx

@@ -0,0 +1,61 @@
+import React from 'react';
+import { AuditData, Result } from './api/polaris';
+
+// --- Fixtures ---
+
+export function makeResult(overrides: Partial<Result> = {}): Result {
+  return {
+    Name: 'my-deploy',
+    Namespace: 'default',
+    Kind: 'Deployment',
+    Results: {},
+    CreatedTime: '2025-01-01T00:00:00Z',
+    ...overrides,
+  };
+}
+
+export function makeAuditData(results: Result[]): AuditData {
+  return {
+    PolarisOutputVersion: '1.0',
+    AuditTime: '2025-01-01T00:00:00Z',
+    SourceType: 'Cluster',
+    SourceName: 'test',
+    DisplayName: 'test',
+    ClusterInfo: { Version: '1.28', Nodes: 3, Pods: 10, Namespaces: 2, Controllers: 5 },
+    Results: results,
+  };
+}
+
+// --- Mock Polaris Context Provider ---
+
+interface MockPolarisProviderProps {
+  data?: AuditData | null;
+  loading?: boolean;
+  error?: string | null;
+  children: React.ReactNode;
+}
+
+// We dynamically import PolarisDataContext to inject mock values.
+// This avoids mocking the hook module — we supply real context with controlled values.
+const PolarisDataContext = React.createContext<{
+  data: AuditData | null;
+  loading: boolean;
+  error: string | null;
+} | null>(null);
+
+export function MockPolarisProvider({
+  data = null,
+  loading = false,
+  error = null,
+  children,
+}: MockPolarisProviderProps) {
+  return (
+    <PolarisDataContext.Provider value={{ data, loading, error }}>
+      {children}
+    </PolarisDataContext.Provider>
+  );
+}
+
+// The context reference used in test-utils must be the SAME object the components import.
+// We achieve this by having component tests mock `usePolarisDataContext` to read from our context.
+export { PolarisDataContext };