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/date-fns/_lib/roundingMethods/index.js

@@ -0,0 +1,19 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.getRoundingMethod = getRoundingMethod;
+var roundingMap = {
+  ceil: Math.ceil,
+  round: Math.round,
+  floor: Math.floor,
+  trunc: function trunc(value) {
+    return value < 0 ? Math.ceil(value) : Math.floor(value);
+  } // Math.trunc is not supported by IE
+};
+
+var defaultRoundingMethod = 'trunc';
+function getRoundingMethod(method) {
+  return method ? roundingMap[method] : roundingMap[defaultRoundingMethod];
+}