perf(web): reuse locale formatters

vehicle-data-platform/apps/web/src/v2/pages/HistoryPage.tsx

@@ -10,6 +10,8 @@ import { QUERY_MEMORY, retainPreviousPageWithinScope } from '../queryPolicy';
 import { usePlatformSession } from '../auth/AuthGate';
 import { canOperate } from '../auth/session';
 
+const historyAxisTimeFormatter = new Intl.DateTimeFormat('zh-CN', { timeZone: 'Asia/Shanghai', month: '2-digit', day: '2-digit', hour: '2-digit', minute: '2-digit', hour12: false });
+
 function HistoryTrend({ response, category, loading, error }: { response?: HistorySeriesResponse; category: string; loading: boolean; error?: string }) {
   const panels = useMemo(() => buildHistorySeriesPanels(response), [response]);
   if (category !== 'location') return <section className="v2-history-trend"><header><strong>聚合趋势</strong></header><div className="v2-history-chart-empty">{category === 'raw' ? '原始报文是离散证据，不生成可能误导的连续趋势；请使用明细与导出。' : '日里程按自然日展示，当前请使用明细表核对起止里程。'}</div></section>;
@@ -28,7 +30,7 @@ function HistoryTrend({ response, category, loading, error }: { response?: Histo
 export function formatAxisTime(value: string) {
   const parsed = new Date(value);
   if (!Number.isFinite(parsed.getTime())) return value.replace('T', ' ').slice(5, 16);
-  return new Intl.DateTimeFormat('zh-CN', { timeZone: 'Asia/Shanghai', month: '2-digit', day: '2-digit', hour: '2-digit', minute: '2-digit', hour12: false }).format(parsed).replace('/', '-');
+  return historyAxisTimeFormatter.format(parsed).replace('/', '-');
 }
 function currentHistoryWindow() {
   const now = new Date(); const pad = (value: number) => String(value).padStart(2, '0');