fix: remove unused variables flagged by code quality bot

Addressed GitHub code quality bot suggestions:
- Removed unused import 'waitFor' from Toast.test.tsx
- Removed unused variable 'saveButton' from featuresets.spec.ts

Both variables were leftover from initial implementation and not needed for test logic.

Author: Mohammod Al Amin Ashik

tests/e2e/specs/featuresets.spec.ts

@@ -192,8 +192,6 @@ test.describe('Config Editor Toast', () => {
       // This is tricky with Monaco editor, so we'll just test the error state
       const editor = page.locator('.monaco-editor');
       if (await editor.isVisible()) {
-        const saveButton = page.getByRole('button', { name: /Save/i });
-        
         // If save is disabled due to invalid JSON, that's the expected behavior
         // The toast would show if we could actually trigger a save with invalid JSON
       }

tests/ts/components/Toast.test.tsx

@@ -1,5 +1,5 @@
 import { describe, it, expect, vi, beforeEach } from 'vitest';
-import { render, screen, waitFor } from '@testing-library/react';
+import { render, screen } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 import { Toast, ToastContainer } from '../../../packages/ui/src/components/common/Toast';