refactor(i18n): U41 残余硬编码中文清零 — 工具函数+审计RDP标签+AIOps分析+Monitor残余+审批选项

18 文件 ~35 处 UI 硬编码中文→t()/i18n.t() 调用:
- agent-utils.ts timeAgo() 秒前/分钟前/小时前
- utils.ts formatDistanceToNow() 分钟前/小时前/天前
- request.ts 响应解析失败错误消息
- ActiveSessionsPanel/HistorySessionsPanel RDP 在线/历史会话标签
- MetricsExplorer 清除/已选/最近1小时
- HostMonitor 当前主机 subtitle
- AIAnalysisResult 证据链 (新增 useTranslation hook)
- capacity-predict.ts 容量预测摘要模板
- ApprovalResourcePage 阿里云/腾讯云/华为云
- ApprovalPermissionPage 堡垒机
- site-monitor/helpers.ts 频率/时间/证书天数格式化
- site-monitor/analytics.ts 证书剩余/检查失败/延迟波动事件
- middleware-monitor MwTargetChartsPanel/MwTrendChart/helpers.ts
- snmp-monitor SnmpMetricTrendChart/SnmpDeviceChartsPanel
- host-monitor/utils.ts 图表点数标签 + PortPolicyDialog 系统进程说明

新增 34 翻译键 (common.duration.secAgo/hourAgo/dayAgo + common.selected/
responseParseError/rdpActiveSessions/rdpHistorySessions/rdpSessionCount/
evidenceChain/last1Hour/currentHost + monitor.lbl 10键 + monitor.siteMonitor
8键 + approval.provider 3键 + approval.permType 1键 +
monitor.portPolicyDialog.systemProcessDesc + aiops.capacity.summary)

zh/en 7813→7847 对齐; tsc -b=0, npm build✓ (17.31s), ESLint=0/43/any=0,
go build=0, 17/17 测试通过

frontend/src/utils/request.ts

@@ -108,7 +108,7 @@ async function request<T = any>(
   try {
     json = await response.json();
   } catch {
-    throw new Error(`HTTP ${response.status}: 响应解析失败`);
+    throw new Error(`HTTP ${response.status}: ${i18n.t('common.responseParseError')}`);
   }
 
   if (!response.ok || (json.code && json.code !== 200)) {