fix(cliproxy): degrade gracefully on GitHub release 403s

- fall back to stale CLIProxy version caches instead of surfacing 500s

- remove duplicate dashboard update-check fetches and disable retry/focus refetch

- add backend and UI regressions for the degraded-path behavior

ui/tests/unit/components/cliproxy/cliproxy-header.test.tsx

@@ -0,0 +1,56 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { render, screen } from '../../../setup/test-utils';
+
+const hookMocks = vi.hoisted(() => ({
+  startAuth: vi.fn(),
+}));
+
+vi.mock('@/hooks/use-cliproxy', () => ({
+  useCliproxyAuth: () => ({
+    data: {
+      authStatus: [],
+    },
+  }),
+  useCliproxyUpdateCheck: () => ({
+    data: {
+      backendLabel: 'CLIProxy Plus',
+      currentVersion: '6.9.23-0',
+      isStable: true,
+      stabilityMessage: undefined,
+    },
+  }),
+}));
+
+vi.mock('@/hooks/use-cliproxy-auth-flow', () => ({
+  useCliproxyAuthFlow: () => ({
+    provider: null,
+    isAuthenticating: false,
+    startAuth: hookMocks.startAuth,
+  }),
+}));
+
+import { CliproxyHeader } from '@/components/cliproxy/cliproxy-header';
+
+describe('CliproxyHeader', () => {
+  const fetchMock = vi.fn<typeof fetch>();
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    fetchMock.mockReset();
+    vi.stubGlobal('fetch', fetchMock);
+  });
+
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it('renders version data from the shared update query without issuing a direct fetch', () => {
+    render(
+      <CliproxyHeader onRefresh={vi.fn()} isRefreshing={false} lastUpdated={new Date()} isRunning />
+    );
+
+    expect(screen.getByText('CLIProxy Plus')).toBeInTheDocument();
+    expect(screen.getByText('v6.9.23-0')).toBeInTheDocument();
+    expect(fetchMock).not.toHaveBeenCalled();
+  });
+});