refactor: BackUrl::selfWithoutBack 统一 selfWithoutBack 构造并修复 currentQuery 依赖

resources/views/admin/plans/index.blade.php

@@ -6,12 +6,7 @@
 @section('content')
 @php
     // back 参数用于“返回上一页（保留上下文）”，但 back 本身不应再包含 back（避免无限嵌套导致 URL 膨胀）
-    $currentQuery = request()->query();
-    unset($currentQuery['back']);
-    $selfWithoutBack = '/' . ltrim(request()->path(), '/');
-    if (count($currentQuery) > 0) {
-        $selfWithoutBack .= '?' . \Illuminate\Support\Arr::query($currentQuery);
-    }
+    $selfWithoutBack = \App\Support\BackUrl::selfWithoutBack();
 
     // 用于构建“从套餐页跳转到订阅/订单页后可返回套餐页”的链接
     $makeSubscriptionUrl = function (array $query) use ($selfWithoutBack) {