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/_baseUpdate.js

@@ -0,0 +1,18 @@
+var baseGet = require('./_baseGet'),
+    baseSet = require('./_baseSet');
+
+/**
+ * The base implementation of `_.update`.
+ *
+ * @private
+ * @param {Object} object The object to modify.
+ * @param {Array|string} path The path of the property to update.
+ * @param {Function} updater The function to produce the updated value.
+ * @param {Function} [customizer] The function to customize path creation.
+ * @returns {Object} Returns `object`.
+ */
+function baseUpdate(object, path, updater, customizer) {
+  return baseSet(object, path, updater(baseGet(object, path)), customizer);
+}
+
+module.exports = baseUpdate;