test(examples/ag-ui): match classified-error copy in error-handling e2e (#695)

#693 replaced the raw stream-failure text with friendly AGENT_ERROR_MESSAGES
copy ("Can't reach the server. Check your connection and try again."), which
no longer contains "fail"/"error" — turning main red on examples/ag-ui — e2e.
The chat example's spec was updated in #693; the ag-ui twin was missed. Mirror
that assertion so the ag-ui error-handling spec asserts the actual copy.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: blove

examples/ag-ui/angular/e2e/error-handling.spec.ts

@@ -13,7 +13,10 @@ test('error handling: failed stream surfaces an alert and the next send recovers
 
   await messageInput(page).fill('say hi briefly');
   await sendButton(page).click();
-  await expect(page.getByRole('alert')).toContainText(/fail|error/i, { timeout: 15_000 });
+  await expect(page.getByRole('alert')).toContainText(
+    /can't reach|connection|server|interrupted|try again/i,
+    { timeout: 15_000 },
+  );
 
   await page.unroute('**/agent');
   await expect(messageInput(page)).toBeEnabled();