fix: 修复缓存监控页面TTL分析时间段选择器点击无响应

为 Select 组件添加 v-model:open 绑定，解决 radix-vue Select 组件
在某些情况下点击无响应的问题。

Fixes #55

frontend/src/views/admin/CacheMonitoring.vue

@@ -46,6 +46,7 @@ const clearingRowAffinityKey = ref<string | null>(null)
 const currentPage = ref(1)
 const pageSize = ref(20)
 const currentTime = ref(Math.floor(Date.now() / 1000))
+const analysisHoursSelectOpen = ref(false)
 
 // ==================== 模型映射缓存 ====================
 
@@ -1056,7 +1057,7 @@ onBeforeUnmount(() => {
             <span class="text-xs text-muted-foreground hidden sm:inline">分析用户请求间隔，推荐合适的缓存 TTL</span>
           </div>
           <div class="flex flex-wrap items-center gap-2">
-            <Select v-model="analysisHours">
+            <Select v-model="analysisHours" v-model:open="analysisHoursSelectOpen">
               <SelectTrigger class="w-24 sm:w-28 h-8">
                 <SelectValue placeholder="时间段" />
               </SelectTrigger>