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/domutils/lib/esm/stringify.d.ts

@@ -0,0 +1,46 @@
+import { AnyNode } from "domhandler";
+import { DomSerializerOptions } from "dom-serializer";
+/**
+ * @category Stringify
+ * @deprecated Use the `dom-serializer` module directly.
+ * @param node Node to get the outer HTML of.
+ * @param options Options for serialization.
+ * @returns `node`'s outer HTML.
+ */
+export declare function getOuterHTML(node: AnyNode | ArrayLike<AnyNode>, options?: DomSerializerOptions): string;
+/**
+ * @category Stringify
+ * @deprecated Use the `dom-serializer` module directly.
+ * @param node Node to get the inner HTML of.
+ * @param options Options for serialization.
+ * @returns `node`'s inner HTML.
+ */
+export declare function getInnerHTML(node: AnyNode, options?: DomSerializerOptions): string;
+/**
+ * Get a node's inner text. Same as `textContent`, but inserts newlines for `<br>` tags. Ignores comments.
+ *
+ * @category Stringify
+ * @deprecated Use `textContent` instead.
+ * @param node Node to get the inner text of.
+ * @returns `node`'s inner text.
+ */
+export declare function getText(node: AnyNode | AnyNode[]): string;
+/**
+ * Get a node's text content. Ignores comments.
+ *
+ * @category Stringify
+ * @param node Node to get the text content of.
+ * @returns `node`'s text content.
+ * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/Node/textContent}
+ */
+export declare function textContent(node: AnyNode | AnyNode[]): string;
+/**
+ * Get a node's inner text, ignoring `<script>` and `<style>` tags. Ignores comments.
+ *
+ * @category Stringify
+ * @param node Node to get the inner text of.
+ * @returns `node`'s inner text.
+ * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/Node/innerText}
+ */
+export declare function innerText(node: AnyNode | AnyNode[]): string;
+//# sourceMappingURL=stringify.d.ts.map