feat(i18n): Dashboard 页面内容国际化迁移 — 3 组件(Dashboard/DashboardCharts/DashboardRecent)硬编码中文改翻译键 + zh-CN/en-US 新增 dashboard.* 121 键(241 total)

- Dashboard.tsx: 标题/副标题/刷新/服务器按钮/StatStrip 7 标签/概览卡片标题 全部 t() 化
- DashboardCharts.tsx: 云成本概览/Top5资源使用/费用分布/月度趋势/环比标签 i18n(computeMonthChange 用 i18n.t 避开非组件上下文)
- DashboardRecent.tsx: 告警消息/证书到期/发布历史/服务器状态/集群状态 5 卡片全量 i18n
- zh-CN.json/en-US.json: dashboard 命名空间扩展 stat/alerts/certificates/releases/serversStatus/clusters/cost/topUsage/system 9 子分组
- 翻译键总数 120→241 (zh-CN/en-US 完全对齐)
- tsc -b=0, npm build=✓(19.01s), 17/17 集成测试通过, Docker healthy

frontend/src/components/dashboard/Dashboard.tsx

@@ -1,5 +1,6 @@
 import { useCallback, useEffect, useState } from 'react';
 import { useNavigate } from 'react-router-dom';
+import { useTranslation } from 'react-i18next';
 import { Button } from '@/components/ui/button';
 import { cn } from '@/lib/utils';
 import { Clock, Server, ArrowRight } from 'lucide-react';
@@ -34,6 +35,7 @@ import type { AlertEventRecord, CertExpiryRecord } from '@/types';
  * 6. 添加页面标题区域的操作入口
  */
 export function Dashboard() {
+  const { t } = useTranslation();
   const navigate = useNavigate();
   const [initialLoading, setInitialLoading] = useState(true);
   const [refreshing, setRefreshing] = useState(false);
@@ -111,8 +113,8 @@ export function Dashboard() {
       {/* Page Header */}
       <div className="dg-page-header">
         <div>
-          <h1 className="dg-page-title">仪表盘</h1>
-          <p className="dg-page-subtitle">实时监控和运维概览 · 最后更新: {new Date().toLocaleTimeString('zh-CN')}</p>
+          <h1 className="dg-page-title">{t('dashboard.title')}</h1>
+          <p className="dg-page-subtitle">{t('dashboard.subtitle')} · {t('dashboard.lastUpdated')}: {new Date().toLocaleTimeString()}</p>
         </div>
         <div className="dg-page-actions">
           <Button
@@ -122,14 +124,14 @@ export function Dashboard() {
             disabled={refreshing}
           >
             <Clock className={cn('h-4 w-4', refreshing && 'animate-spin')} />
-            {refreshing ? '刷新中' : '刷新'}
+            {refreshing ? t('dashboard.refreshing') : t('dashboard.refresh')}
           </Button>
           <Button
             className="dg-btn-primary"
             onClick={() => navigate('/servers')}
           >
             <Server className="h-4 w-4" />
-            服务器
+            {t('dashboard.servers')}
             <ArrowRight className="h-3.5 w-3.5" />
           </Button>
         </div>
@@ -139,13 +141,13 @@ export function Dashboard() {
       <div className="animate-fade-in-delay-1">
         <StatStrip
           items={[
-            { label: '服务器', value: serverStats?.total ?? 0, color: 'blue' },
-            { label: '运行中', value: serverStats?.running ?? 0, color: 'emerald' },
-            { label: 'K8s 集群', value: k8sStats?.total ?? 0, color: 'purple' },
-            { label: '健康集群', value: k8sStats?.healthy ?? 0, color: 'cyan' },
-            { label: '告警', value: alertStats?.firing ?? 0, color: alertStats?.firing > 0 ? 'red' : 'muted' },
-            { label: '严重', value: alertStats?.critical ?? 0, color: 'red' },
-            { label: '本月成本', value: `¥${Number(costStats?.month_cost ?? 0).toLocaleString()}`, color: 'amber' },
+            { label: t('dashboard.stat.servers'), value: serverStats?.total ?? 0, color: 'blue' },
+            { label: t('dashboard.stat.running'), value: serverStats?.running ?? 0, color: 'emerald' },
+            { label: t('dashboard.stat.k8sClusters'), value: k8sStats?.total ?? 0, color: 'purple' },
+            { label: t('dashboard.stat.healthyClusters'), value: k8sStats?.healthy ?? 0, color: 'cyan' },
+            { label: t('dashboard.stat.alerts'), value: alertStats?.firing ?? 0, color: alertStats?.firing > 0 ? 'red' : 'muted' },
+            { label: t('dashboard.stat.critical'), value: alertStats?.critical ?? 0, color: 'red' },
+            { label: t('dashboard.stat.monthlyCost'), value: `¥${Number(costStats?.month_cost ?? 0).toLocaleString()}`, color: 'amber' },
           ]}
         />
       </div>