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/detect-newline/index.js

@@ -0,0 +1,21 @@
+'use strict';
+
+const detectNewline = string => {
+	if (typeof string !== 'string') {
+		throw new TypeError('Expected a string');
+	}
+
+	const newlines = string.match(/(?:\r?\n)/g) || [];
+
+	if (newlines.length === 0) {
+		return;
+	}
+
+	const crlf = newlines.filter(newline => newline === '\r\n').length;
+	const lf = newlines.length - crlf;
+
+	return crlf > lf ? '\r\n' : '\n';
+};
+
+module.exports = detectNewline;
+module.exports.graceful = string => (typeof string === 'string' && detectNewline(string)) || '\n';