refactor(site-subscriptions): dedupe show page back actions

tests/Feature/AdminSiteSubscriptionShowIndexLinkKeepsContextTest.php

@@ -66,5 +66,13 @@ class AdminSiteSubscriptionShowIndexLinkKeepsContextTest extends TestCase
 
         $res->assertSee('返回订阅列表（保留上下文）');
         $res->assertSee($expectedIndexUrl, false);
+
+        // 当传入有效 back 时，应优先显示“返回上一页”并隐藏该兜底按钮（避免重复入口噪音）
+        $res2 = $this->get('/admin/site-subscriptions/' . $sub->id . '?' . Arr::query([
+            'back' => '/admin',
+        ]));
+        $res2->assertOk();
+        $res2->assertSee('返回上一页（保留上下文）');
+        $res2->assertDontSee('返回订阅列表（保留上下文）');
     }
 }