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/dns-packet/classes.js

@@ -0,0 +1,23 @@
+'use strict'
+
+exports.toString = function (klass) {
+  switch (klass) {
+    case 1: return 'IN'
+    case 2: return 'CS'
+    case 3: return 'CH'
+    case 4: return 'HS'
+    case 255: return 'ANY'
+  }
+  return 'UNKNOWN_' + klass
+}
+
+exports.toClass = function (name) {
+  switch (name.toUpperCase()) {
+    case 'IN': return 1
+    case 'CS': return 2
+    case 'CH': return 3
+    case 'HS': return 4
+    case 'ANY': return 255
+  }
+  return 0
+}