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/stylelint/lib/utils/isBlocklessAtRuleAfterSameNameBlocklessAtRule.js

@@ -0,0 +1,23 @@
+'use strict';
+
+const getPreviousNonSharedLineCommentNode = require('./getPreviousNonSharedLineCommentNode');
+const isBlocklessAtRuleAfterBlocklessAtRule = require('./isBlocklessAtRuleAfterBlocklessAtRule');
+const { isAtRule } = require('./typeGuards');
+
+/**
+ * @param {import('postcss').AtRule} atRule
+ * @returns {boolean}
+ */
+module.exports = function isBlocklessAtRuleAfterSameNameBlocklessAtRule(atRule) {
+	if (!isBlocklessAtRuleAfterBlocklessAtRule(atRule)) {
+		return false;
+	}
+
+	const previousNode = getPreviousNonSharedLineCommentNode(atRule);
+
+	if (previousNode && isAtRule(previousNode)) {
+		return previousNode.name === atRule.name;
+	}
+
+	return false;
+};