fix(logout): purge the namespaced Cache API store on logout

GET responses with an ETag were persisted into the @SUPERSET-UI/CONNECTION
Cache API namespace and retained across sessions, with no purge on logout. The
logout handler already cleared the persisted redux localStorage and session
storage; extend it to also delete the namespaced Cache API store so cached
responses are not retained on the device after the session ends.

Best-effort (the promise is not awaited since logout navigates away). Extends
the existing RightMenu logout test to assert the cache namespace is purged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

superset-frontend/src/features/home/RightMenu.test.tsx

@@ -401,6 +401,10 @@ test('Logs out and clears local storage item redux', async () => {
   expect(localStorage.getItem('redux')).not.toBeNull();
   expect(sessionStorage.getItem('login_attempted')).not.toBeNull();
 
+  // Mock the Cache API so we can assert the namespaced store is purged.
+  const deleteMock = jest.fn().mockResolvedValue(true);
+  (global as any).caches = { delete: deleteMock };
+
   await userEvent.hover(await screen.findByText(/Settings/i));
 
   // Simulate user clicking the logout button
@@ -412,6 +416,10 @@ test('Logs out and clears local storage item redux', async () => {
     expect(localStorage.getItem('redux')).toBeNull();
     expect(sessionStorage.getItem('login_attempted')).toBeNull();
   });
+  // The namespaced Cache API store is purged on logout.
+  expect(deleteMock).toHaveBeenCalledWith('@SUPERSET-UI/CONNECTION');
+
+  delete (global as any).caches;
 });
 
 test('shows logout button when not embedded', async () => {

superset-frontend/src/features/home/RightMenu.tsx

@@ -28,6 +28,7 @@ import {
   getExtensionsRegistry,
   isFeatureEnabled,
   FeatureFlag,
+  CACHE_KEY,
 } from '@superset-ui/core';
 import {
   styled,
@@ -353,6 +354,14 @@ const RightMenu = ({
     try {
       window.localStorage.removeItem('redux');
       window.sessionStorage.removeItem('login_attempted');
+      // Purge the namespaced Cache API store so cached GET responses are not
+      // retained on the device after the session ends. Best-effort: the
+      // returned promise is not awaited since logout navigates away.
+      if (typeof caches !== 'undefined') {
+        caches.delete(CACHE_KEY).catch(() => {
+          /* best-effort: ignore cache deletion failures */
+        });
+      }
     } catch (error) {
       console.warn('Failed to clear storage on logout:', error);
     }