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/collect-v8-coverage/index.d.ts

@@ -0,0 +1,7 @@
+/// <reference types="node" />
+import { Profiler } from 'inspector';
+export declare type V8Coverage = ReadonlyArray<Profiler.ScriptCoverage>;
+export declare class CoverageInstrumenter {
+  startInstrumenting(): Promise<void>;
+  stopInstrumenting(): Promise<V8Coverage>;
+}