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/_baseToPairs.js

@@ -0,0 +1,18 @@
+var arrayMap = require('./_arrayMap');
+
+/**
+ * The base implementation of `_.toPairs` and `_.toPairsIn` which creates an array
+ * of key-value pairs for `object` corresponding to the property names of `props`.
+ *
+ * @private
+ * @param {Object} object The object to query.
+ * @param {Array} props The property names to get values for.
+ * @returns {Object} Returns the key-value pairs.
+ */
+function baseToPairs(object, props) {
+  return arrayMap(props, function(key) {
+    return [key, object[key]];
+  });
+}
+
+module.exports = baseToPairs;