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/npm-normalize-package-bin/test/array.js

@@ -0,0 +1,37 @@
+const normalize = require('../')
+const t = require('tap')
+
+t.test('benign array', async t => {
+  const pkg = { name: 'hello', version: 'world', bin: ['./x/y', 'y/z', './a'] }
+  const expect = { name: 'hello', version: 'world', bin: {
+    y: 'x/y',
+    z: 'y/z',
+    a: 'a',
+  } }
+  t.strictSame(normalize(pkg), expect)
+  t.strictSame(normalize(normalize(pkg)), expect, 'double sanitize ok')
+})
+
+t.test('conflicting array', async t => {
+  const pkg = { name: 'hello', version: 'world', bin: ['./x/y', 'z/y', './a'] }
+  const expect = { name: 'hello', version: 'world', bin: {
+    y: 'z/y',
+    a: 'a',
+  } }
+  t.strictSame(normalize(pkg), expect)
+  t.strictSame(normalize(normalize(pkg)), expect, 'double sanitize ok')
+})
+
+t.test('slashy array', async t => {
+  const pkg = { name: 'hello', version: 'world', bin: [ '/etc/passwd' ] }
+  const expect = { name: 'hello', version: 'world', bin: { passwd: 'etc/passwd' } }
+  t.strictSame(normalize(pkg), expect)
+  t.strictSame(normalize(normalize(pkg)), expect, 'double sanitize ok')
+})
+
+t.test('dotty array', async t => {
+  const pkg = { name: 'hello', version: 'world', bin: ['../../../../etc/passwd'] }
+  const expect = { name: 'hello', version: 'world', bin: { passwd: 'etc/passwd' } }
+  t.strictSame(normalize(pkg), expect)
+  t.strictSame(normalize(normalize(pkg)), expect, 'double sanitize ok')
+})