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/node-exports-info/getCategoryFlags.d.ts

@@ -0,0 +1,13 @@
+import type { Category } from './types';
+
+declare namespace getCategoryFlags {
+	interface CategoryFlags {
+		patterns: boolean;
+		patternTrailers: boolean;
+		dirSlash: boolean;
+	}
+}
+
+declare function getCategoryFlags(category: Category): getCategoryFlags.CategoryFlags;
+
+export = getCategoryFlags;