feat(react-integration): add React polyfills and ensure global availability

- Introduced a React polyfill to prevent undefined errors in dependencies by making React globally available in both window and globalThis.
- Updated the App component to allow optional children prop for improved flexibility.
- Created a new dnd-kit-wrapper utility to ensure React is available globally before importing @dnd-kit utilities.

worklenz-frontend/src/App.tsx

@@ -21,7 +21,7 @@ import { Language } from './features/i18n/localesSlice';
 import logger from './utils/errorLogger';
 import { SuspenseFallback } from './components/suspense-fallback/suspense-fallback';
 
-const App: React.FC<{ children: React.ReactNode }> = ({ children }) => {
+const App: React.FC<{ children?: React.ReactNode }> = ({ children }) => {
   const themeMode = useAppSelector(state => state.themeReducer.mode);
   const language = useAppSelector(state => state.localesReducer.lng);
 

worklenz-frontend/src/index.tsx

@@ -1,3 +1,6 @@
+// Import React polyfill first to ensure React is available globally
+import './utils/react-polyfill';
+
 import React from 'react';
 import ReactDOM from 'react-dom/client';
 import './index.css';

worklenz-frontend/src/utils/dnd-kit-wrapper.ts

@@ -0,0 +1,12 @@
+import React from 'react';
+
+// Ensure React is available globally before any @dnd-kit imports
+if (typeof globalThis !== 'undefined') {
+  (globalThis as any).React = React;
+}
+
+// Re-export @dnd-kit utilities with React dependency assured
+export * from '@dnd-kit/core';
+export * from '@dnd-kit/sortable';
+export * from '@dnd-kit/modifiers';
+export * from '@dnd-kit/utilities'; 

worklenz-frontend/src/utils/react-polyfill.ts

@@ -0,0 +1,12 @@
+import React from 'react';
+
+// Polyfill React hooks globally to prevent undefined errors in dependencies
+if (typeof window !== 'undefined') {
+  // Ensure React is available globally
+  (window as any).React = React;
+}
+
+// Also ensure it's available in globalThis for ES modules
+if (typeof globalThis !== 'undefined') {
+  (globalThis as any).React = React;
+}