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/postcss/lib/comment.d.ts

@@ -0,0 +1,67 @@
+import Container from './container.js'
+import Node, { NodeProps } from './node.js'
+
+declare namespace Comment {
+  export interface CommentRaws extends Record<string, unknown> {
+    /**
+     * The space symbols before the node.
+     */
+    before?: string
+
+    /**
+     * The space symbols between `/*` and the comment’s text.
+     */
+    left?: string
+
+    /**
+     * The space symbols between the comment’s text.
+     */
+    right?: string
+  }
+
+  export interface CommentProps extends NodeProps {
+    /** Information used to generate byte-to-byte equal node string as it was in the origin input. */
+    raws?: CommentRaws
+    /** Content of the comment. */
+    text: string
+  }
+
+  export { Comment_ as default }
+}
+
+/**
+ * It represents a class that handles
+ * [CSS comments](https://developer.mozilla.org/en-US/docs/Web/CSS/Comments)
+ *
+ * ```js
+ * Once (root, { Comment }) {
+ *   const note = new Comment({ text: 'Note: …' })
+ *   root.append(note)
+ * }
+ * ```
+ *
+ * Remember that CSS comments inside selectors, at-rule parameters,
+ * or declaration values will be stored in the `raws` properties
+ * explained above.
+ */
+declare class Comment_ extends Node {
+  parent: Container | undefined
+  raws: Comment.CommentRaws
+  type: 'comment'
+  /**
+   * The comment's text.
+   */
+  get text(): string
+
+  set text(value: string)
+
+  constructor(defaults?: Comment.CommentProps)
+  assign(overrides: Comment.CommentProps | object): this
+  clone(overrides?: Partial<Comment.CommentProps>): this
+  cloneAfter(overrides?: Partial<Comment.CommentProps>): this
+  cloneBefore(overrides?: Partial<Comment.CommentProps>): this
+}
+
+declare class Comment extends Comment_ {}
+
+export = Comment