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/css-loader/dist/runtime/sourceMaps.js

@@ -0,0 +1,16 @@
+"use strict";
+
+module.exports = function (item) {
+  var content = item[1];
+  var cssMapping = item[3];
+  if (!cssMapping) {
+    return content;
+  }
+  if (typeof btoa === "function") {
+    var base64 = btoa(unescape(encodeURIComponent(JSON.stringify(cssMapping))));
+    var data = "sourceMappingURL=data:application/json;charset=utf-8;base64,".concat(base64);
+    var sourceMapping = "/*# ".concat(data, " */");
+    return [content].concat([sourceMapping]).join("\n");
+  }
+  return [content].join("\n");
+};