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/decamelize/index.js

@@ -0,0 +1,13 @@
+'use strict';
+module.exports = function (str, sep) {
+	if (typeof str !== 'string') {
+		throw new TypeError('Expected a string');
+	}
+
+	sep = typeof sep === 'undefined' ? '_' : sep;
+
+	return str
+		.replace(/([a-z\d])([A-Z])/g, '$1' + sep + '$2')
+		.replace(/([A-Z]+)([A-Z][a-z\d]+)/g, '$1' + sep + '$2')
+		.toLowerCase();
+};