fix(epay): allow custom payment types via string input

- Replace select dropdown with string input for `type`

plugins/Epay/Plugin.php

@@ -45,12 +45,8 @@ class Plugin extends AbstractPlugin implements PaymentInterface
             ],
             'type' => [
                 'label' => '支付类型',
-                'type' => 'select',
+                'type' => 'string',
-                'options' => [
+                'description' => '支付类型，如: alipay, wxpay, qqpay 等，可自定义'
-                    ['value' => 'alipay', 'label' => '支付宝'],
-                    ['value' => 'wxpay', 'label' => '微信支付'],
-                    ['value' => 'qqpay', 'label' => 'QQ钱包']
-                ]
             ],
         ];
     }