test(06-05): add failing dead-end AuthSplash test for exhausted redirect guard (D-11)

apps/pwa/src/components/CalendarShell.test.tsx

@@ -217,4 +217,14 @@ describe('CalendarShell — CAL-03 render smoke', () => {
     renderWithClient(<CalendarShell />)
     // Error renders asynchronously after query settles
   })
+
+  it('renders dead-end AuthSplash when redirect guard is already exhausted (D-11)', async () => {
+    // Simulate the one-shot guard having already fired (prior redirect attempt)
+    sessionStorage.setItem('familysync.loginRedirectAttempted', '1')
+    ;(fetchMe as Mock).mockRejectedValue(new Error('401'))
+    renderWithClient(<CalendarShell />)
+    // After the auth error and the guard is exhausted, dead-end copy must be visible
+    const tapToRetry = await screen.findByText(/Tap here to try again/i)
+    expect(tapToRetry).toBeDefined()
+  })
 })