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/escalade/sync/index.d.mts

@@ -0,0 +1,9 @@
+export type Callback = (
+	directory: string,
+	files: string[],
+) => string | false | void;
+
+export default function (
+	directory: string,
+	callback: Callback,
+): string | void;

node_modules/escalade/sync/index.d.ts

@@ -0,0 +1,13 @@
+declare namespace escalade {
+	export type Callback = (
+		directory: string,
+		files: string[],
+	) => string | false | void;
+}
+
+declare function escalade(
+	directory: string,
+	callback: escalade.Callback,
+): string | void;
+
+export = escalade;

node_modules/escalade/sync/index.js

@@ -0,0 +1,18 @@
+const { dirname, resolve } = require('path');
+const { readdirSync, statSync } = require('fs');
+
+module.exports = function (start, callback) {
+	let dir = resolve('.', start);
+	let tmp, stats = statSync(dir);
+
+	if (!stats.isDirectory()) {
+		dir = dirname(dir);
+	}
+
+	while (true) {
+		tmp = callback(dir, readdirSync(dir));
+		if (tmp) return resolve(dir, tmp);
+		dir = dirname(tmp = dir);
+		if (tmp === dir) break;
+	}
+}

node_modules/escalade/sync/index.mjs

@@ -0,0 +1,18 @@
+import { dirname, resolve } from 'path';
+import { readdirSync, statSync } from 'fs';
+
+export default function (start, callback) {
+	let dir = resolve('.', start);
+	let tmp, stats = statSync(dir);
+
+	if (!stats.isDirectory()) {
+		dir = dirname(dir);
+	}
+
+	while (true) {
+		tmp = callback(dir, readdirSync(dir));
+		if (tmp) return resolve(dir, tmp);
+		dir = dirname(tmp = dir);
+		if (tmp === dir) break;
+	}
+}