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/forwarded/package.json

@@ -0,0 +1,45 @@
+{
+  "name": "forwarded",
+  "description": "Parse HTTP X-Forwarded-For header",
+  "version": "0.2.0",
+  "contributors": [
+    "Douglas Christopher Wilson <doug@somethingdoug.com>"
+  ],
+  "license": "MIT",
+  "keywords": [
+    "x-forwarded-for",
+    "http",
+    "req"
+  ],
+  "repository": "jshttp/forwarded",
+  "devDependencies": {
+    "beautify-benchmark": "0.2.4",
+    "benchmark": "2.1.4",
+    "deep-equal": "1.0.1",
+    "eslint": "7.27.0",
+    "eslint-config-standard": "14.1.1",
+    "eslint-plugin-import": "2.23.4",
+    "eslint-plugin-node": "11.1.0",
+    "eslint-plugin-promise": "4.3.1",
+    "eslint-plugin-standard": "4.1.0",
+    "mocha": "8.4.0",
+    "nyc": "15.1.0"
+  },
+  "files": [
+    "LICENSE",
+    "HISTORY.md",
+    "README.md",
+    "index.js"
+  ],
+  "engines": {
+    "node": ">= 0.6"
+  },
+  "scripts": {
+    "bench": "node benchmark/index.js",
+    "lint": "eslint .",
+    "test": "mocha --reporter spec --bail --check-leaks test/",
+    "test-ci": "nyc --reporter=lcov --reporter=text npm test",
+    "test-cov": "nyc --reporter=html --reporter=text npm test",
+    "version": "node scripts/version-history.js && git add HISTORY.md"
+  }
+}