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-dev-server/client/utils/parseURL.js

@@ -0,0 +1,36 @@
+import getCurrentScriptSource from "./getCurrentScriptSource.js";
+
+/**
+ * @param {string} resourceQuery
+ * @returns {{ [key: string]: string | boolean }}
+ */
+function parseURL(resourceQuery) {
+  /** @type {{ [key: string]: string }} */
+  var options = {};
+  if (typeof resourceQuery === "string" && resourceQuery !== "") {
+    var searchParams = resourceQuery.slice(1).split("&");
+    for (var i = 0; i < searchParams.length; i++) {
+      var pair = searchParams[i].split("=");
+      options[pair[0]] = decodeURIComponent(pair[1]);
+    }
+  } else {
+    // Else, get the url from the <script> this file was called with.
+    var scriptSource = getCurrentScriptSource();
+    var scriptSourceURL;
+    try {
+      // The placeholder `baseURL` with `window.location.href`,
+      // is to allow parsing of path-relative or protocol-relative URLs,
+      // and will have no effect if `scriptSource` is a fully valid URL.
+      scriptSourceURL = new URL(scriptSource, self.location.href);
+    } catch (error) {
+      // URL parsing failed, do nothing.
+      // We will still proceed to see if we can recover using `resourceQuery`
+    }
+    if (scriptSourceURL) {
+      options = scriptSourceURL;
+      options.fromCurrentScript = true;
+    }
+  }
+  return options;
+}
+export default parseURL;