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/spawnd/README.md

@@ -0,0 +1,31 @@
+# spawnd
+
+[![npm version](https://img.shields.io/npm/v/spawnd.svg)](https://www.npmjs.com/package/spawnd)
+[![npm dm](https://img.shields.io/npm/dm/spawnd.svg)](https://www.npmjs.com/package/spawnd)
+[![npm dt](https://img.shields.io/npm/dt/spawnd.svg)](https://www.npmjs.com/package/spawnd)
+
+Spawn a process inter-dependent with parent process.
+
+```
+npm install spawnd
+```
+
+## Usage
+
+```js
+import { spawnd } from "spawnd";
+
+const proc = spawnd("node server.js", { shell: true });
+
+proc.destroy().then(() => {
+  console.log("Destroyed!");
+});
+```
+
+## API
+
+### spawnd(command[, args[, options]])
+
+Exactly the same API as [Node.js spawn](https://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options).
+
+It returns a [Child Process](https://nodejs.org/api/child_process.html#child_process_class_childprocess) that exposes a destroy method that will kill the process.