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/zipObject.js

@@ -0,0 +1,24 @@
+var assignValue = require('./_assignValue'),
+    baseZipObject = require('./_baseZipObject');
+
+/**
+ * This method is like `_.fromPairs` except that it accepts two arrays,
+ * one of property identifiers and one of corresponding values.
+ *
+ * @static
+ * @memberOf _
+ * @since 0.4.0
+ * @category Array
+ * @param {Array} [props=[]] The property identifiers.
+ * @param {Array} [values=[]] The property values.
+ * @returns {Object} Returns the new object.
+ * @example
+ *
+ * _.zipObject(['a', 'b'], [1, 2]);
+ * // => { 'a': 1, 'b': 2 }
+ */
+function zipObject(props, values) {
+  return baseZipObject(props || [], values || [], assignValue);
+}
+
+module.exports = zipObject;