feat(balpay): 添加支付宝支付扩展的钩子

- 在 Extension.php 中添加 getHooks 方法，返回 BalpayHook 类
- 新增 BalpayHook 类以处理支付宝支付相关的钩子事件

src/Extension.php

@@ -3,6 +3,7 @@ declare(strict_types=1);
 
 namespace SixShop\Balpay;
 
+use SixShop\Balpay\Hook\BalpayHook;
 use SixShop\Core\ExtensionAbstract;
 use SixShop\Payment\Contracts\PaymentExtensionInterface;
 use SixShop\Payment\Contracts\PaymentProviderInterface;
@@ -19,4 +20,11 @@ class Extension extends ExtensionAbstract implements PaymentExtensionInterface
     {
         return dirname(__DIR__);
     }
+
+    public function getHooks(): array
+    {
+        return [
+            BalpayHook::class
+        ];
+    }
 }