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/cross-spawn/lib/util/escapeCommand.js

@@ -0,0 +1,12 @@
+'use strict';
+
+var escapeArgument = require('./escapeArgument');
+
+function escapeCommand(command) {
+    // Do not escape if this command is not dangerous..
+    // We do this so that commands like "echo" or "ifconfig" work
+    // Quoting them, will make them unaccessible
+    return /^[a-z0-9_-]+$/i.test(command) ? command : escapeArgument(command, true);
+}
+
+module.exports = escapeCommand;