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/fast-uri/benchmark/ws-is-secure.mjs

@@ -0,0 +1,65 @@
+import { Bench } from 'tinybench'
+import { wsIsSecure } from '../lib/schemes.js'
+
+const benchWsIsSecure = new Bench({ name: 'wsIsSecure' })
+
+const wsComponentAttributeSecureTrue = {
+  scheme: 'ws',
+  secure: true,
+}
+
+const wsComponentAttributeSecureFalse = {
+  scheme: 'ws',
+  secure: false,
+}
+
+const wssComponent = {
+  scheme: 'wss',
+}
+
+const wssComponentMixedCase = {
+  scheme: 'Wss',
+}
+
+const wssComponentUpperCase = {
+  scheme: 'WSS',
+}
+
+const httpComponent = {
+  scheme: 'http',
+}
+
+console.assert(wsIsSecure(wsComponentAttributeSecureTrue) === true, 'wsComponentAttributeSecureTrue should be secure')
+console.assert(wsIsSecure(wsComponentAttributeSecureFalse) === false, 'wsComponentAttributeSecureFalse should not be secure')
+console.assert(wsIsSecure(wssComponent) === true, 'wssComponent should be secure')
+console.assert(wsIsSecure(wssComponentMixedCase) === true, 'wssComponentMixedCase should be secure')
+console.assert(wsIsSecure(wssComponentUpperCase) === true, 'wssComponentUpperCase should be secure')
+console.assert(wsIsSecure(httpComponent) === false, 'httpComponent should not be secure')
+
+benchWsIsSecure.add(JSON.stringify(wsComponentAttributeSecureFalse), function () {
+  wsIsSecure(wsComponentAttributeSecureFalse)
+})
+
+benchWsIsSecure.add(JSON.stringify(wsComponentAttributeSecureTrue), function () {
+  wsIsSecure(wsComponentAttributeSecureTrue)
+})
+
+benchWsIsSecure.add(JSON.stringify(wssComponent), function () {
+  wsIsSecure(wssComponent)
+})
+
+benchWsIsSecure.add(JSON.stringify(wssComponentMixedCase), function () {
+  wsIsSecure(wssComponentMixedCase)
+})
+
+benchWsIsSecure.add(JSON.stringify(wssComponentUpperCase), function () {
+  wsIsSecure(wssComponentUpperCase)
+})
+
+benchWsIsSecure.add(JSON.stringify(httpComponent), function () {
+  wsIsSecure(httpComponent)
+})
+
+await benchWsIsSecure.run()
+console.log(benchWsIsSecure.name)
+console.table(benchWsIsSecure.table())