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/basic-ftp/dist/parseListDOS.d.ts

@@ -0,0 +1,12 @@
+import { FileInfo } from "./FileInfo";
+/**
+ * Returns true if a given line might be a DOS-style listing.
+ *
+ * - Example: `12-05-96  05:03PM       <DIR>          myDir`
+ */
+export declare function testLine(line: string): boolean;
+/**
+ * Parse a single line of a DOS-style directory listing.
+ */
+export declare function parseLine(line: string): FileInfo | undefined;
+export declare function transformList(files: FileInfo[]): FileInfo[];