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/dom-ready/build-module/index.js

@@ -0,0 +1,45 @@
+/**
+ * @typedef {() => void} Callback
+ *
+ * TODO: Remove this typedef and inline `() => void` type.
+ *
+ * This typedef is used so that a descriptive type is provided in our
+ * automatically generated documentation.
+ *
+ * An in-line type `() => void` would be preferable, but the generated
+ * documentation is `null` in that case.
+ *
+ * @see https://github.com/WordPress/gutenberg/issues/18045
+ */
+
+/**
+ * Specify a function to execute when the DOM is fully loaded.
+ *
+ * @param {Callback} callback A function to execute after the DOM is ready.
+ *
+ * @example
+ * ```js
+ * import domReady from '@wordpress/dom-ready';
+ *
+ * domReady( function() {
+ * 	//do something after DOM loads.
+ * } );
+ * ```
+ *
+ * @return {void}
+ */
+export default function domReady(callback) {
+  if (typeof document === 'undefined') {
+    return;
+  }
+  if (document.readyState === 'complete' ||
+  // DOMContentLoaded + Images/Styles/etc loaded, so we call directly.
+  document.readyState === 'interactive' // DOMContentLoaded fires at this point, so we call directly.
+  ) {
+    return void callback();
+  }
+
+  // DOMContentLoaded has not fired yet, delay callback until then.
+  document.addEventListener('DOMContentLoaded', callback);
+}
+//# sourceMappingURL=index.js.map

node_modules/@wordpress/dom-ready/build-module/index.js.map

@@ -0,0 +1 @@
+{"version":3,"names":["domReady","callback","document","readyState","addEventListener"],"sources":["@wordpress/dom-ready/src/index.js"],"sourcesContent":["/**\n * @typedef {() => void} Callback\n *\n * TODO: Remove this typedef and inline `() => void` type.\n *\n * This typedef is used so that a descriptive type is provided in our\n * automatically generated documentation.\n *\n * An in-line type `() => void` would be preferable, but the generated\n * documentation is `null` in that case.\n *\n * @see https://github.com/WordPress/gutenberg/issues/18045\n */\n\n/**\n * Specify a function to execute when the DOM is fully loaded.\n *\n * @param {Callback} callback A function to execute after the DOM is ready.\n *\n * @example\n * ```js\n * import domReady from '@wordpress/dom-ready';\n *\n * domReady( function() {\n * \t//do something after DOM loads.\n * } );\n * ```\n *\n * @return {void}\n */\nexport default function domReady( callback ) {\n\tif ( typeof document === 'undefined' ) {\n\t\treturn;\n\t}\n\n\tif (\n\t\tdocument.readyState === 'complete' || // DOMContentLoaded + Images/Styles/etc loaded, so we call directly.\n\t\tdocument.readyState === 'interactive' // DOMContentLoaded fires at this point, so we call directly.\n\t) {\n\t\treturn void callback();\n\t}\n\n\t// DOMContentLoaded has not fired yet, delay callback until then.\n\tdocument.addEventListener( 'DOMContentLoaded', callback );\n}\n"],"mappings":"AAAA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;;AAEA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA;AACA,eAAe,SAASA,QAAQA,CAAEC,QAAQ,EAAG;EAC5C,IAAK,OAAOC,QAAQ,KAAK,WAAW,EAAG;IACtC;EACD;EAEA,IACCA,QAAQ,CAACC,UAAU,KAAK,UAAU;EAAI;EACtCD,QAAQ,CAACC,UAAU,KAAK,aAAa,CAAC;EAAA,EACrC;IACD,OAAO,KAAKF,QAAQ,CAAC,CAAC;EACvB;;EAEA;EACAC,QAAQ,CAACE,gBAAgB,CAAE,kBAAkB,EAAEH,QAAS,CAAC;AAC1D","ignoreList":[]}