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/@babel/runtime/helpers/toPrimitive.js

@@ -0,0 +1,12 @@
+var _typeof = require("./typeof.js")["default"];
+function toPrimitive(t, r) {
+  if ("object" != _typeof(t) || !t) return t;
+  var e = t[Symbol.toPrimitive];
+  if (void 0 !== e) {
+    var i = e.call(t, r || "default");
+    if ("object" != _typeof(i)) return i;
+    throw new TypeError("@@toPrimitive must return a primitive value.");
+  }
+  return ("string" === r ? String : Number)(t);
+}
+module.exports = toPrimitive, module.exports.__esModule = true, module.exports["default"] = module.exports;