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/eslint/lib/rules/require-yield.js

@@ -0,0 +1,77 @@
+/**
+ * @fileoverview Rule to flag the generator functions that does not have yield.
+ * @author Toru Nagashima
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../shared/types').Rule} */
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "Require generator functions to contain `yield`",
+            recommended: true,
+            url: "https://eslint.org/docs/latest/rules/require-yield"
+        },
+
+        schema: [],
+
+        messages: {
+            missingYield: "This generator function does not have 'yield'."
+        }
+    },
+
+    create(context) {
+        const stack = [];
+
+        /**
+         * If the node is a generator function, start counting `yield` keywords.
+         * @param {Node} node A function node to check.
+         * @returns {void}
+         */
+        function beginChecking(node) {
+            if (node.generator) {
+                stack.push(0);
+            }
+        }
+
+        /**
+         * If the node is a generator function, end counting `yield` keywords, then
+         * reports result.
+         * @param {Node} node A function node to check.
+         * @returns {void}
+         */
+        function endChecking(node) {
+            if (!node.generator) {
+                return;
+            }
+
+            const countYield = stack.pop();
+
+            if (countYield === 0 && node.body.body.length > 0) {
+                context.report({ node, messageId: "missingYield" });
+            }
+        }
+
+        return {
+            FunctionDeclaration: beginChecking,
+            "FunctionDeclaration:exit": endChecking,
+            FunctionExpression: beginChecking,
+            "FunctionExpression:exit": endChecking,
+
+            // Increases the count of `yield` keyword.
+            YieldExpression() {
+
+                if (stack.length > 0) {
+                    stack[stack.length - 1] += 1;
+                }
+            }
+        };
+    }
+};