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/babel-loader/lib/Error.js

@@ -0,0 +1,31 @@
+"use strict";
+
+const STRIP_FILENAME_RE = /^[^:]+: /;
+const format = err => {
+  if (err instanceof SyntaxError) {
+    err.name = "SyntaxError";
+    err.message = err.message.replace(STRIP_FILENAME_RE, "");
+    err.hideStack = true;
+  } else if (err instanceof TypeError) {
+    err.name = null;
+    err.message = err.message.replace(STRIP_FILENAME_RE, "");
+    err.hideStack = true;
+  }
+  return err;
+};
+class LoaderError extends Error {
+  constructor(err) {
+    super();
+    const {
+      name,
+      message,
+      codeFrame,
+      hideStack
+    } = format(err);
+    this.name = "BabelLoaderError";
+    this.message = `${name ? `${name}: ` : ""}${message}\n\n${codeFrame}\n`;
+    this.hideStack = hideStack;
+    Error.captureStackTrace(this, this.constructor);
+  }
+}
+module.exports = LoaderError;