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/rules/value-list-max-empty-lines/index.js

@@ -0,0 +1,65 @@
+'use strict';
+
+const getDeclarationValue = require('../../utils/getDeclarationValue');
+const report = require('../../utils/report');
+const ruleMessages = require('../../utils/ruleMessages');
+const setDeclarationValue = require('../../utils/setDeclarationValue');
+const validateOptions = require('../../utils/validateOptions');
+const { isNumber } = require('../../utils/validateTypes');
+
+const ruleName = 'value-list-max-empty-lines';
+
+const messages = ruleMessages(ruleName, {
+	expected: (max) => `Expected no more than ${max} empty ${max === 1 ? 'line' : 'lines'}`,
+});
+
+const meta = {
+	url: 'https://stylelint.io/user-guide/rules/value-list-max-empty-lines',
+	fixable: true,
+};
+
+/** @type {import('stylelint').Rule} */
+const rule = (primary, _secondaryOptions, context) => {
+	const maxAdjacentNewlines = primary + 1;
+
+	return (root, result) => {
+		const validOptions = validateOptions(result, ruleName, {
+			actual: primary,
+			possible: isNumber,
+		});
+
+		if (!validOptions) {
+			return;
+		}
+
+		const violatedCRLFNewLinesRegex = new RegExp(`(?:\r\n){${maxAdjacentNewlines + 1},}`);
+		const violatedLFNewLinesRegex = new RegExp(`\n{${maxAdjacentNewlines + 1},}`);
+		const allowedLFNewLinesString = context.fix ? '\n'.repeat(maxAdjacentNewlines) : '';
+		const allowedCRLFNewLinesString = context.fix ? '\r\n'.repeat(maxAdjacentNewlines) : '';
+
+		root.walkDecls((decl) => {
+			const value = getDeclarationValue(decl);
+
+			if (context.fix) {
+				const newValueString = value
+					.replace(new RegExp(violatedLFNewLinesRegex, 'gm'), allowedLFNewLinesString)
+					.replace(new RegExp(violatedCRLFNewLinesRegex, 'gm'), allowedCRLFNewLinesString);
+
+				setDeclarationValue(decl, newValueString);
+			} else if (violatedLFNewLinesRegex.test(value) || violatedCRLFNewLinesRegex.test(value)) {
+				report({
+					message: messages.expected(primary),
+					node: decl,
+					index: 0,
+					result,
+					ruleName,
+				});
+			}
+		});
+	};
+};
+
+rule.ruleName = ruleName;
+rule.messages = messages;
+rule.meta = meta;
+module.exports = rule;