docs(flutter/license): use canonical xuqm_flutter_license import path

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs-site/docs/flutter/license.md

@@ -36,7 +36,7 @@ flutter:
 
 ```dart
 import 'package:flutter/services.dart' show rootBundle;
-import 'package:xuqm_flutter_license/xuqm_license.dart';
+import 'package:xuqm_flutter_license/xuqm_flutter_license.dart';
 
 Future<void> verifyLicense() async {
   // 从 assets 读取加密文件