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/es-abstract/2023/IsDetachedBuffer.js

@@ -0,0 +1,28 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var $byteLength = require('array-buffer-byte-length');
+var availableTypedArrays = require('available-typed-arrays')();
+var callBound = require('call-bound');
+var isArrayBuffer = require('is-array-buffer');
+var isSharedArrayBuffer = require('is-shared-array-buffer');
+
+var $sabByteLength = callBound('SharedArrayBuffer.prototype.byteLength', true);
+
+// https://262.ecma-international.org/8.0/#sec-isdetachedbuffer
+
+module.exports = function IsDetachedBuffer(arrayBuffer) {
+	var isSAB = isSharedArrayBuffer(arrayBuffer);
+	if (!isArrayBuffer(arrayBuffer) && !isSAB) {
+		throw new $TypeError('Assertion failed: `arrayBuffer` must be an Object with an [[ArrayBufferData]] internal slot');
+	}
+	if ((isSAB ? $sabByteLength : $byteLength)(arrayBuffer) === 0) {
+		try {
+			new global[availableTypedArrays[0]](arrayBuffer); // eslint-disable-line no-new
+		} catch (error) {
+			return !!error && error.name === 'TypeError';
+		}
+	}
+	return false;
+};