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/extract-zip/cli.js

@@ -0,0 +1,19 @@
+#!/usr/bin/env node
+
+/* eslint-disable no-process-exit */
+
+var extract = require('./')
+
+var args = process.argv.slice(2)
+var source = args[0]
+var dest = args[1] || process.cwd()
+if (!source) {
+  console.error('Usage: extract-zip foo.zip <targetDirectory>')
+  process.exit(1)
+}
+
+extract(source, { dir: dest })
+  .catch(function (err) {
+    console.error('error!', err)
+    process.exit(1)
+  })