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-config-prettier/bin/validators.js

@@ -0,0 +1,63 @@
+"use strict";
+
+// These validator functions answer the question “Is the config valid?” – return
+// `false` if the options DO conflict with Prettier, and `true` if they don’t.
+
+module.exports = {
+  "curly"({ options }) {
+    if (options.length === 0) {
+      return true;
+    }
+
+    const firstOption = options[0];
+    return firstOption !== "multi-line" && firstOption !== "multi-or-nest";
+  },
+
+  "lines-around-comment"({ options }) {
+    if (options.length === 0) {
+      return false;
+    }
+
+    const firstOption = options[0];
+    return Boolean(
+      firstOption &&
+        firstOption.allowBlockStart &&
+        firstOption.allowBlockEnd &&
+        firstOption.allowObjectStart &&
+        firstOption.allowObjectEnd &&
+        firstOption.allowArrayStart &&
+        firstOption.allowArrayEnd
+    );
+  },
+
+  "no-confusing-arrow"({ options }) {
+    if (options.length === 0) {
+      return false;
+    }
+
+    const firstOption = options[0];
+    return firstOption ? firstOption.allowParens === false : false;
+  },
+
+  "no-tabs"({ options }) {
+    if (options.length === 0) {
+      return false;
+    }
+
+    const firstOption = options[0];
+    return Boolean(firstOption && firstOption.allowIndentationTabs);
+  },
+
+  "vue/html-self-closing"({ options }) {
+    if (options.length === 0) {
+      return false;
+    }
+
+    const firstOption = options[0];
+    return Boolean(
+      firstOption && firstOption.html && firstOption.html.void === "any"
+      // Enable when Prettier supports SVG: https://github.com/prettier/prettier/issues/5322
+      // && firstOption.svg === "any"
+    );
+  },
+};