Add Redis-backed chat queue

ai_knowledge_base_v2/apps/admin-web/src/App.vue

@@ -302,6 +302,15 @@ const systemSettingSections: SystemSettingSection[] = [
         max: 3600,
         description: "请求在排队中超过该时间后自动结束并提示用户稍后再试。",
       },
+      {
+        key: "chat_active_lease_seconds",
+        label: "问答执行租约（秒）",
+        type: "number",
+        defaultValue: 900,
+        min: 60,
+        max: 86400,
+        description: "Redis 全局队列中执行名额的自动过期时间，防止 worker 异常退出后长期占用并发名额。",
+      },
     ],
   },
   {