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/_baseGet.js

@@ -0,0 +1,24 @@
+var castPath = require('./_castPath'),
+    toKey = require('./_toKey');
+
+/**
+ * The base implementation of `_.get` without support for default values.
+ *
+ * @private
+ * @param {Object} object The object to query.
+ * @param {Array|string} path The path of the property to get.
+ * @returns {*} Returns the resolved value.
+ */
+function baseGet(object, path) {
+  path = castPath(path, object);
+
+  var index = 0,
+      length = path.length;
+
+  while (object != null && index < length) {
+    object = object[toKey(path[index++])];
+  }
+  return (index && index == length) ? object : undefined;
+}
+
+module.exports = baseGet;