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/lodash/_stringToArray.js

@@ -0,0 +1,18 @@
+var asciiToArray = require('./_asciiToArray'),
+    hasUnicode = require('./_hasUnicode'),
+    unicodeToArray = require('./_unicodeToArray');
+
+/**
+ * Converts `string` to an array.
+ *
+ * @private
+ * @param {string} string The string to convert.
+ * @returns {Array} Returns the converted array.
+ */
+function stringToArray(string) {
+  return hasUnicode(string)
+    ? unicodeToArray(string)
+    : asciiToArray(string);
+}
+
+module.exports = stringToArray;