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/prettier-linter-helpers/index.d.ts

@@ -0,0 +1,41 @@
+/**
+ * Converts invisible characters to a commonly recognizable visible form.
+ * @param {string} str - The string with invisibles to convert.
+ * @returns {string} The converted string.
+ */
+export function showInvisibles(str: string): string;
+
+export type Difference =
+  | {
+      operation: 'insert';
+      insertText: string;
+      offset: number;
+    }
+  | {
+      operation: 'delete';
+      deleteText: string;
+      offset: number;
+    }
+  | {
+      operation: 'replace';
+      insertText: string;
+      deleteText: string;
+      offset: number;
+    };
+
+/**
+ * Generate results for differences between source code and formatted version.
+ *
+ * @param {string} source - The original source.
+ * @param {string} prettierSource - The Prettier formatted source.
+ * @returns {Difference[]} - An array containing { operation, offset, insertText, deleteText }
+ */
+export function generateDifferences(
+  source: string,
+  prettierSource: string
+): Difference[];
+export namespace generateDifferences {
+  let INSERT: 'insert';
+  let DELETE: 'delete';
+  let REPLACE: 'replace';
+}