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/webpack/hot/lazy-compilation-universal.js

@@ -0,0 +1,18 @@
+"use strict";
+
+/* global __resourceQuery */
+
+var isNodeLikeEnv =
+	typeof global !== "undefined" && typeof global.process !== "undefined";
+
+var handler = isNodeLikeEnv
+	? require("./lazy-compilation-node")
+	: require("./lazy-compilation-web");
+
+handler.setUrl(decodeURIComponent(__resourceQuery.slice(1)));
+
+/**
+ * @param {{ data: string, onError: (err: Error) => void, active: boolean, module: module }} options options
+ * @returns {() => void} function to destroy response
+ */
+module.exports = handler;