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/tsconfig-paths/lib/__tests__/match-path-sync.test.js

@@ -0,0 +1,15 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+var match_path_sync_1 = require("../match-path-sync");
+var Tests = require("./data/match-path-data");
+describe("match-path-sync", function () {
+    Tests.tests.forEach(function (t) {
+        return it(t.name, function () {
+            var matchPath = (0, match_path_sync_1.createMatchPath)(t.absoluteBaseUrl, t.paths, t.mainFields, t.addMatchAll);
+            var result = matchPath(t.requestedModule, function (_) { return t.packageJson; }, function (name) { return t.existingFiles.indexOf(name) !== -1; }, t.extensions);
+            // assert.equal(result, t.expectedPath);
+            expect(result).toBe(t.expectedPath);
+        });
+    });
+});
+//# sourceMappingURL=match-path-sync.test.js.map