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/v8-to-istanbul/README.md

@@ -0,0 +1,88 @@
+# v8-to-istanbul
+
+[![Build Status](https://img.shields.io/github/actions/workflow/status/istanbuljs/v8-to-istanbul/ci.yaml?branch=master)](https://github.com/istanbuljs/v8-to-istanbul/actions)
+[![Conventional Commits](https://img.shields.io/badge/Conventional%20Commits-1.0.0-yellow.svg)](https://conventionalcommits.org)
+![nycrc config on GitHub](https://img.shields.io/nycrc/istanbuljs/v8-to-istanbul)
+
+converts from v8 coverage format to [istanbul's coverage format](https://github.com/gotwarlost/istanbul/blob/master/coverage.json.md).
+
+## Usage
+
+```js
+const v8toIstanbul = require('v8-to-istanbul')
+// the path to the original source-file is required, as its contents are
+// used during the conversion algorithm.
+const converter = v8toIstanbul('./path-to-instrumented-file.js')
+await converter.load() // this is required due to async file reading.
+// provide an array of coverage information in v8 format.
+converter.applyCoverage([
+  {
+    "functionName": "",
+    "ranges": [
+      {
+        "startOffset": 0,
+        "endOffset": 520,
+        "count": 1
+      }
+    ],
+    "isBlockCoverage": true
+  },
+  // ...
+])
+// output coverage information in a form that can
+// be consumed by Istanbul.
+console.info(JSON.stringify(converter.toIstanbul()))
+```
+
+## Ignoring Uncovered Lines
+
+Sometimes you might find yourself wanting to ignore uncovered lines
+in your application (for example, perhaps you run your tests in Linux, but
+there's code that only executes on Windows).
+
+To ignore lines, use the special comment `/* v8 ignore next */`.
+
+**NOTE**: Before version `9.2.0` the ignore hint had to contain `c8` keyword, e.g. `/* c8 ignore ...`.
+
+### ignoring the next line
+
+```js
+const myVariable = 99
+/* v8 ignore next */
+if (process.platform === 'win32') console.info('hello world')
+```
+
+### ignoring the next N lines
+
+```js
+const myVariable = 99
+/* v8 ignore next 3 */
+if (process.platform === 'win32') {
+  console.info('hello world')
+}
+```
+
+### ignoring all lines until told
+
+```js
+/* v8 ignore start */
+function dontMindMe() {
+  // ...
+}
+/* v8 ignore stop */
+```
+
+### ignoring the same line as the comment
+
+```js
+const myVariable = 99
+const os = process.platform === 'darwin' ? 'OSXy' /* v8 ignore next */ : 'Windowsy' 
+```
+
+## Testing
+
+To execute tests, simply run:
+
+```bash
+npm test
+```