fix: prevent asset conflicts between React and Grid.js versions

Add coexistence checks to all enqueue methods to prevent loading
both React and Grid.js assets simultaneously.

Changes:
- ReactAdmin.php: Only enqueue React assets when ?react=1
- Init.php: Skip Grid.js when React active on admin pages
- Form.php, Coupon.php, Access.php: Restore classic assets when ?react=0
- Customer.php, Product.php, License.php: Add coexistence checks

Now the toggle between Classic and React versions works correctly.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

node_modules/@wordpress/scripts/utils/process.js

@@ -0,0 +1,23 @@
+const getAsBooleanFromENV = ( name ) => {
+	const value = process.env[ name ];
+	return !! value && value !== 'false' && value !== '0';
+};
+
+const getArgsFromCLI = ( excludePrefixes ) => {
+	const args = process.argv.slice( 2 );
+	if ( excludePrefixes ) {
+		return args.filter( ( arg ) => {
+			return ! excludePrefixes.some( ( prefix ) =>
+				arg.startsWith( prefix )
+			);
+		} );
+	}
+	return args;
+};
+
+module.exports = {
+	exit: process.exit,
+	getAsBooleanFromENV,
+	getArgsFromCLI,
+	getCurrentWorkingDirectory: process.cwd,
+};