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

tests/unit/web-server/cliproxy-stats-routes-version-fallback.test.ts

@@ -0,0 +1,46 @@
+import { describe, expect, it } from 'bun:test';
+
+describe('cliproxy-stats-routes version fallback', () => {
+  it('returns a degraded update-check payload instead of propagating a 500', async () => {
+    const { resolveCliproxyUpdateCheckPayload } = await import(
+      '../../../src/web-server/routes/cliproxy-stats-routes'
+    );
+
+    const body = await resolveCliproxyUpdateCheckPayload('plus', {
+      checkCliproxyUpdateFn: async () => {
+        throw new Error('GitHub API error: HTTP 403');
+      },
+      getInstalledVersionFn: () => '6.6.80',
+    });
+
+    expect(body).toMatchObject({
+      hasUpdate: false,
+      currentVersion: '6.6.80',
+      latestVersion: '6.6.80',
+      backend: 'plus',
+      backendLabel: 'CLIProxy Plus',
+      fromCache: true,
+    });
+  });
+
+  it('returns a degraded versions payload instead of propagating a 500', async () => {
+    const { resolveCliproxyVersionsPayload } = await import(
+      '../../../src/web-server/routes/cliproxy-stats-routes'
+    );
+
+    const body = await resolveCliproxyVersionsPayload('plus', {
+      fetchAllVersionsFn: async () => {
+        throw new Error('GitHub API error: HTTP 403');
+      },
+      getInstalledVersionFn: () => '6.6.80',
+    });
+
+    expect(body).toMatchObject({
+      versions: ['6.6.80'],
+      latestStable: '6.6.80',
+      latest: '6.6.80',
+      currentVersion: '6.6.80',
+      fromCache: true,
+    });
+  });
+});