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/istanbul-lib-report/README.md

@@ -0,0 +1,43 @@
+# istanbul-lib-report
+
+[![Greenkeeper badge](https://badges.greenkeeper.io/istanbuljs/istanbul-lib-report.svg)](https://greenkeeper.io/)
+[![Build Status](https://travis-ci.org/istanbuljs/istanbul-lib-report.svg?branch=master)](https://travis-ci.org/istanbuljs/istanbul-lib-report)
+
+Core reporting utilities for istanbul.
+
+## Example usage
+
+```js
+const libReport = require('istanbul-lib-report');
+const reports = require('istanbul-reports');
+
+// coverageMap, for instance, obtained from istanbul-lib-coverage
+const coverageMap;
+
+const configWatermarks = {
+  statements: [50, 80],
+  functions: [50, 80],
+  branches: [50, 80],
+  lines: [50, 80]
+};
+
+// create a context for report generation
+const context = libReport.createContext({
+  dir: 'report/output/dir',
+  // The summarizer to default to (may be overridden by some reports)
+  // values can be nested/flat/pkg. Defaults to 'pkg'
+  defaultSummarizer: 'nested',
+  watermarks: configWatermarks,
+  coverageMap,
+})
+
+// create an instance of the relevant report class, passing the
+// report name e.g. json/html/html-spa/text
+const report = reports.create('json', {
+  skipEmpty: configSkipEmpty,
+  skipFull: configSkipFull
+})
+
+// call execute to synchronously create and write the report to disk
+report.execute(context)
+```