feat(i18n): 全量中英文国际化改造

- 翻译 en-US.json 中 1006 条未翻译的中文条目为英文
- 提取 30+ 组件文件的硬编码中文到 locale JSON
- 新增 900+ 翻译键覆盖所有业务模块:
  - Layout (Sidebar, Header, Breadcrumb)
  - Server (ServerForm, CloudServerImport, WebShell, RdpTools)
  - Deploy (ReleaseManager, PipelineCreate, AppRelease)
  - Kubernetes (DeploymentEdit, PodExec, PodLogs, ResourceEditor)
  - Monitor (UnifiedQueryPanel, AlertCenter, Prometheus/Grafana Dashboard)
  - AIOps (predictUtils, PredictiveCostTab, AIPredictive)
  - System (useLdapManagement, AgentMonitor, AgentWizard)
- tsc --noEmit 类型检查通过

frontend/src/components/monitor/dashboard/GrafanaDashboard.tsx

@@ -507,20 +507,20 @@ const DatasourceToolbar: React.FC<{
   <div className="flex items-center gap-2 mb-3 flex-wrap">
     <Select value={activeId} onValueChange={onChange}>
       <SelectTrigger className="w-[280px] h-8 text-xs dg-input">
-        <SelectValue placeholder="选择数据源" />
+        <SelectValue placeholder={t('monitor.datasourceToolbar.selectDatasource')} />
       </SelectTrigger>
       <SelectContent className="dg-input">
         {sources.map(ds => (
           <SelectItem key={String(ds.id)} value={String(ds.id)}>
-            {ds.name || ds.url}{ds.is_default ? ' · 默认' : ''}
+            {ds.name || ds.url}{ds.is_default ? t('monitor.datasourceToolbar.defaultSuffix') : ''}
           </SelectItem>
         ))}
       </SelectContent>
     </Select>
     <Button variant="outline" size="sm" className="h-8 text-xs gap-1" onClick={onRefresh} disabled={refreshing}>
-      <RefreshCw className={cn('w-3 h-3', refreshing && 'animate-spin')} />刷新数据源
+      <RefreshCw className={cn('w-3 h-3', refreshing && 'animate-spin')} />{t('monitor.datasourceToolbar.refreshDatasource')}
     </Button>
-    <span className="text-[11px] text-[var(--dg-text-muted)]">共 {sources.length} 个数据源，当前仅查询选中项</span>
+    <span className="text-[11px] text-[var(--dg-text-muted)]">{t('monitor.datasourceToolbar.datasourceSummary', { count: sources.length })}</span>
   </div>
 );