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/deep-is/test/NaN.js

@@ -0,0 +1,16 @@
+var test = require('tape');
+var equal = require('../');
+
+test('NaN and 0 values', function (t) {
+    t.ok(equal(NaN, NaN));
+    t.notOk(equal(0, NaN));
+    t.ok(equal(0, 0));
+    t.notOk(equal(0, 1));
+    t.end();
+});
+
+
+test('nested NaN values', function (t) {
+    t.ok(equal([ NaN, 1, NaN ], [ NaN, 1, NaN ]));
+    t.end();
+});

node_modules/deep-is/test/cmp.js

@@ -0,0 +1,23 @@
+var test = require('tape');
+var equal = require('../');
+
+test('equal', function (t) {
+    t.ok(equal(
+        { a : [ 2, 3 ], b : [ 4 ] },
+        { a : [ 2, 3 ], b : [ 4 ] }
+    ));
+    t.end();
+});
+
+test('not equal', function (t) {
+    t.notOk(equal(
+        { x : 5, y : [6] },
+        { x : 5, y : 6 }
+    ));
+    t.end();
+});
+
+test('nested nulls', function (t) {
+    t.ok(equal([ null, null, null ], [ null, null, null ]));
+    t.end();
+});

node_modules/deep-is/test/neg-vs-pos-0.js

@@ -0,0 +1,15 @@
+var test = require('tape');
+var equal = require('../');
+
+test('0 values', function (t) {
+    t.ok(equal( 0,  0), ' 0 ===  0');
+    t.ok(equal( 0, +0), ' 0 === +0');
+    t.ok(equal(+0, +0), '+0 === +0');
+    t.ok(equal(-0, -0), '-0 === -0');
+
+    t.notOk(equal(-0,  0), '-0 !==  0');
+    t.notOk(equal(-0, +0), '-0 !== +0');
+
+    t.end();
+});
+