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/pac-resolver/dist/isPlainHostName.d.ts

@@ -0,0 +1,18 @@
+/**
+ * True iff there is no domain name in the hostname (no dots).
+ *
+ * Examples:
+ *
+ * ``` js
+ * isPlainHostName("www")
+ *   // is true.
+ *
+ * isPlainHostName("www.netscape.com")
+ *   // is false.
+ * ```
+ *
+ * @param {String} host The hostname from the URL (excluding port number).
+ * @return {Boolean}
+ */
+export default function isPlainHostName(host: string): boolean;
+//# sourceMappingURL=isPlainHostName.d.ts.map