Enhance: site subscriptions index show safe back link

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

@@ -37,6 +37,16 @@
 <div class="card mb-20">
     <p class="muted muted-tight">这里是总台视角的订阅目录页，承接“套餐 -> 订阅 -> 平台订单”的收费主链中间层。</p>
     <p class="muted">当前阶段先做到：可访问列表、可筛选、统计摘要；后续再接：订阅激活服务 / 续费 / 取消 / 对账。</p>
+
+    @php
+        $incomingBack = (string) request()->query('back', '');
+        $safeBack = str_starts_with($incomingBack, '/') ? $incomingBack : '';
+    @endphp
+    @if($safeBack)
+        <div class="mt-10">
+            <a href="{{ $safeBack }}" class="muted">← 返回上一页（保留上下文）</a>
+        </div>
+    @endif
 </div>
 
 <div class="card mb-20">