Fix comprehensive lint and type errors across codebase

- Replace explicit 'any' types with 'unknown' or specific types
- Fix Jest DOM test setup with proper type definitions
- Resolve NODE_ENV assignment errors using Object.defineProperty
- Fix React Hook dependency warnings with useCallback patterns
- Remove unused variables and add appropriate ESLint disables
- Update documentation with groups feature information
- Ensure all tests pass with proper TypeScript compliance

🤖 Generated with [Claude Code](https://claude.ai/code)

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

components/__tests__/Toast.test.tsx

@@ -1,4 +1,4 @@
-import { render, screen, fireEvent, waitFor, act } from '@testing-library/react';
+import { render, screen, fireEvent, act } from '@testing-library/react';
 import { ToastComponent, ToastContainer, Toast, ToastType } from '../Toast';
 
 // Mock timer functions