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/@wordpress/private-apis/build-module/implementation.js

@@ -0,0 +1,183 @@
+/**
+ * wordpress/private-apis – the utilities to enable private cross-package
+ * exports of private APIs.
+ *
+ * This "implementation.js" file is needed for the sake of the unit tests. It
+ * exports more than the public API of the package to aid in testing.
+ */
+
+/**
+ * The list of core modules allowed to opt-in to the private APIs.
+ */
+const CORE_MODULES_USING_PRIVATE_APIS = ['@wordpress/block-directory', '@wordpress/block-editor', '@wordpress/block-library', '@wordpress/blocks', '@wordpress/commands', '@wordpress/components', '@wordpress/core-commands', '@wordpress/core-data', '@wordpress/customize-widgets', '@wordpress/data', '@wordpress/edit-post', '@wordpress/edit-site', '@wordpress/edit-widgets', '@wordpress/editor', '@wordpress/format-library', '@wordpress/interface', '@wordpress/patterns', '@wordpress/preferences', '@wordpress/reusable-blocks', '@wordpress/router', '@wordpress/dataviews'];
+
+/**
+ * A list of core modules that already opted-in to
+ * the privateApis package.
+ *
+ * @type {string[]}
+ */
+const registeredPrivateApis = [];
+
+/*
+ * Warning for theme and plugin developers.
+ *
+ * The use of private developer APIs is intended for use by WordPress Core
+ * and the Gutenberg plugin exclusively.
+ *
+ * Dangerously opting in to using these APIs is NOT RECOMMENDED. Furthermore,
+ * the WordPress Core philosophy to strive to maintain backward compatibility
+ * for third-party developers DOES NOT APPLY to private APIs.
+ *
+ * THE CONSENT STRING FOR OPTING IN TO THESE APIS MAY CHANGE AT ANY TIME AND
+ * WITHOUT NOTICE. THIS CHANGE WILL BREAK EXISTING THIRD-PARTY CODE. SUCH A
+ * CHANGE MAY OCCUR IN EITHER A MAJOR OR MINOR RELEASE.
+ */
+const requiredConsent = 'I know using unstable features means my theme or plugin will inevitably break in the next version of WordPress.';
+
+/** @type {boolean} */
+let allowReRegistration;
+// The safety measure is meant for WordPress core where IS_WORDPRESS_CORE
+// is set to true.
+// For the general use-case, the re-registration should be allowed by default
+// Let's default to true, then. Try/catch will fall back to "true" even if the
+// environment variable is not explicitly defined.
+try {
+  allowReRegistration = process.env.IS_WORDPRESS_CORE ? false : true;
+} catch (error) {
+  allowReRegistration = true;
+}
+
+/**
+ * Called by a @wordpress package wishing to opt-in to accessing or exposing
+ * private private APIs.
+ *
+ * @param {string} consent    The consent string.
+ * @param {string} moduleName The name of the module that is opting in.
+ * @return {{lock: typeof lock, unlock: typeof unlock}} An object containing the lock and unlock functions.
+ */
+export const __dangerousOptInToUnstableAPIsOnlyForCoreModules = (consent, moduleName) => {
+  if (!CORE_MODULES_USING_PRIVATE_APIS.includes(moduleName)) {
+    throw new Error(`You tried to opt-in to unstable APIs as module "${moduleName}". ` + 'This feature is only for JavaScript modules shipped with WordPress core. ' + 'Please do not use it in plugins and themes as the unstable APIs will be removed ' + 'without a warning. If you ignore this error and depend on unstable features, ' + 'your product will inevitably break on one of the next WordPress releases.');
+  }
+  if (!allowReRegistration && registeredPrivateApis.includes(moduleName)) {
+    // This check doesn't play well with Story Books / Hot Module Reloading
+    // and isn't included in the Gutenberg plugin. It only matters in the
+    // WordPress core release.
+    throw new Error(`You tried to opt-in to unstable APIs as module "${moduleName}" which is already registered. ` + 'This feature is only for JavaScript modules shipped with WordPress core. ' + 'Please do not use it in plugins and themes as the unstable APIs will be removed ' + 'without a warning. If you ignore this error and depend on unstable features, ' + 'your product will inevitably break on one of the next WordPress releases.');
+  }
+  if (consent !== requiredConsent) {
+    throw new Error(`You tried to opt-in to unstable APIs without confirming you know the consequences. ` + 'This feature is only for JavaScript modules shipped with WordPress core. ' + 'Please do not use it in plugins and themes as the unstable APIs will removed ' + 'without a warning. If you ignore this error and depend on unstable features, ' + 'your product will inevitably break on the next WordPress release.');
+  }
+  registeredPrivateApis.push(moduleName);
+  return {
+    lock,
+    unlock
+  };
+};
+
+/**
+ * Binds private data to an object.
+ * It does not alter the passed object in any way, only
+ * registers it in an internal map of private data.
+ *
+ * The private data can't be accessed by any other means
+ * than the `unlock` function.
+ *
+ * @example
+ * ```js
+ * const object = {};
+ * const privateData = { a: 1 };
+ * lock( object, privateData );
+ *
+ * object
+ * // {}
+ *
+ * unlock( object );
+ * // { a: 1 }
+ * ```
+ *
+ * @param {any} object      The object to bind the private data to.
+ * @param {any} privateData The private data to bind to the object.
+ */
+function lock(object, privateData) {
+  if (!object) {
+    throw new Error('Cannot lock an undefined object.');
+  }
+  if (!(__private in object)) {
+    object[__private] = {};
+  }
+  lockedData.set(object[__private], privateData);
+}
+
+/**
+ * Unlocks the private data bound to an object.
+ *
+ * It does not alter the passed object in any way, only
+ * returns the private data paired with it using the `lock()`
+ * function.
+ *
+ * @example
+ * ```js
+ * const object = {};
+ * const privateData = { a: 1 };
+ * lock( object, privateData );
+ *
+ * object
+ * // {}
+ *
+ * unlock( object );
+ * // { a: 1 }
+ * ```
+ *
+ * @param {any} object The object to unlock the private data from.
+ * @return {any} The private data bound to the object.
+ */
+function unlock(object) {
+  if (!object) {
+    throw new Error('Cannot unlock an undefined object.');
+  }
+  if (!(__private in object)) {
+    throw new Error('Cannot unlock an object that was not locked before. ');
+  }
+  return lockedData.get(object[__private]);
+}
+const lockedData = new WeakMap();
+
+/**
+ * Used by lock() and unlock() to uniquely identify the private data
+ * related to a containing object.
+ */
+const __private = Symbol('Private API ID');
+
+// Unit tests utilities:
+
+/**
+ * Private function to allow the unit tests to allow
+ * a mock module to access the private APIs.
+ *
+ * @param {string} name The name of the module.
+ */
+export function allowCoreModule(name) {
+  CORE_MODULES_USING_PRIVATE_APIS.push(name);
+}
+
+/**
+ * Private function to allow the unit tests to set
+ * a custom list of allowed modules.
+ */
+export function resetAllowedCoreModules() {
+  while (CORE_MODULES_USING_PRIVATE_APIS.length) {
+    CORE_MODULES_USING_PRIVATE_APIS.pop();
+  }
+}
+/**
+ * Private function to allow the unit tests to reset
+ * the list of registered private apis.
+ */
+export function resetRegisteredPrivateApis() {
+  while (registeredPrivateApis.length) {
+    registeredPrivateApis.pop();
+  }
+}
+//# sourceMappingURL=implementation.js.map