refactor(i18n): U40 Monitor + Agent 子组件残余硬编码中文 i18n 补全 — 14 文件 ~50 处→0

- ContextSwitchCard: CTX/IRQ/次 → t()
- ProcessTable: agentWaitData/cpuUsagePercent → t()
- FDUsageCard: fdHandles → t()
- PortMonitorTab: 黑名单/白名单/策略配置/暂无端口数据 → t()
- PortPolicyDialog: 白名单全量上报/黑名单仅上报/端口列表/逗号分隔/白名单无需配置/已输入端口 → t()
- HostTimeRangePicker: 时间范围/自定义/取消/应用 → t()
- DualLineChart: 接收/发送 → t(), i18n.t→useTranslation hook
- ZoomableAreaChart: 暂无数据 → t()
- SiteResultsPanel: 选择任务/次/可用率/立即拨测/SSL证书预警/到期/剩余/阈值/天 → t()
- MiddlewareMonitor: Redis单机集群/上次更新/添加平台默认/暂无实例 → t()
- SiteMonitor: subtitle → t()
- SNMPMonitor: 标题/采集间隔/IP地址/OID模板/SNMP版本/确认/暂无设备/采集指标/暂无指标 → t()
- HealthProbeSection: TCP目标地址/TCP端口 → t()
- AgentAlerts: Agent告警/刷新/未恢复/已恢复/恢复/新建规则/创建第一条规则 → i18n.t()

新增 monitor.lbl 46 语义化翻译键 + agent.alerts 6 键
zh/en 7762→7814 对齐
tsc -b=0, npm build✓ (16.88s), ESLint=0/43/any=0, go build=0, 17/17 测试通过

frontend/src/components/agent/AgentAlerts.tsx

@@ -113,12 +113,12 @@ export function AgentAlerts() {
       {/* 页头 */}
       <div className="flex items-center justify-between">
         <div>
-          <h2 className="text-xl font-semibold text-[var(--dg-text-primary)]">Agent 告警</h2>
+          <h2 className="text-xl font-semibold text-[var(--dg-text-primary)]">{i18n.t('agent.alerts.title')}</h2>
           <p className="text-sm dg-text-secondary mt-0.5"> {i18n.t('agent.alerts.thresholdTriggered')} </p>
         </div>
         <Button variant="outline" size="sm" onClick={loadData} disabled={loading} className="dg-input text-[var(--dg-text-secondary)] hover:bg-[var(--dg-bg-hover)]">
           <RefreshCw className={`h-4 w-4 mr-1.5 ${loading ? 'animate-spin' : ''}`} />
-          刷新
+          {i18n.t('common.refresh')}
         </Button>
       </div>
 
@@ -137,7 +137,7 @@ export function AgentAlerts() {
               onClick={() => setResolvedView(false)}
               className={!resolvedView ? 'bg-blue-600 hover:bg-blue-700 text-white' : 'dg-input text-[var(--dg-text-secondary)]'}
             >
-              未恢复
+              {i18n.t('agent.alerts.unresolved')}
             </Button>
             <Button
               size="sm"
@@ -145,7 +145,7 @@ export function AgentAlerts() {
               onClick={() => setResolvedView(true)}
               className={resolvedView ? 'bg-blue-600 hover:bg-blue-700 text-white' : 'dg-input text-[var(--dg-text-secondary)]'}
             >
-              已恢复
+              {i18n.t('agent.alerts.resolved')}
             </Button>
           </div>
 
@@ -207,7 +207,7 @@ export function AgentAlerts() {
                           className="shrink-0 h-8 dg-input dg-text-green hover:bg-emerald-500/10 hover:dg-text-green"
                         >
                           <CheckCircle className="h-3.5 w-3.5 mr-1" />
-                          恢复
+                          {i18n.t('agent.alerts.resolve')}
                         </Button>
                       )}
                     </div>
@@ -223,7 +223,7 @@ export function AgentAlerts() {
           <div className="flex justify-end">
             <Button size="sm" onClick={openCreateRule} className="bg-blue-600 hover:bg-blue-700 text-white">
               <Plus className="h-4 w-4 mr-1.5" />
-              新建规则
+              {i18n.t('agent.alerts.newRule')}
             </Button>
           </div>
 
@@ -241,7 +241,7 @@ export function AgentAlerts() {
                 <p className="dg-text-secondary"> {i18n.t('monitor.noRules')} </p>
                 <Button size="sm" onClick={openCreateRule} className="mt-4 bg-blue-600 hover:bg-blue-700 text-white">
                   <Plus className="h-4 w-4 mr-1.5" />
-                  创建第一条规则
+                  {i18n.t('agent.alerts.createFirstRule')}
                 </Button>
               </CardContent>
             </Card>