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/esm/parse/_lib/Parser.js

@@ -0,0 +1,31 @@
+import _classCallCheck from "@babel/runtime/helpers/esm/classCallCheck";
+import _createClass from "@babel/runtime/helpers/esm/createClass";
+import _defineProperty from "@babel/runtime/helpers/esm/defineProperty";
+import { ValueSetter } from "./Setter.js";
+export var Parser = /*#__PURE__*/function () {
+  function Parser() {
+    _classCallCheck(this, Parser);
+    _defineProperty(this, "incompatibleTokens", void 0);
+    _defineProperty(this, "priority", void 0);
+    _defineProperty(this, "subPriority", void 0);
+  }
+  _createClass(Parser, [{
+    key: "run",
+    value: function run(dateString, token, match, options) {
+      var result = this.parse(dateString, token, match, options);
+      if (!result) {
+        return null;
+      }
+      return {
+        setter: new ValueSetter(result.value, this.validate, this.set, this.priority, this.subPriority),
+        rest: result.rest
+      };
+    }
+  }, {
+    key: "validate",
+    value: function validate(_utcDate, _value, _options) {
+      return true;
+    }
+  }]);
+  return Parser;
+}();