feat: add memory settings page

frontend/src/core/utils/datetime.ts

@@ -1,7 +1,27 @@
 import { formatDistanceToNow } from "date-fns";
+import { enUS as dateFnsEnUS, zhCN as dateFnsZhCN } from "date-fns/locale";
 
-export function formatTimeAgo(date: Date | string | number) {
+import { detectLocale, type Locale } from "@/core/i18n";
+import { getLocaleFromCookie } from "@/core/i18n/cookies";
+
+function getDateFnsLocale(locale: Locale) {
+  switch (locale) {
+    case "zh-CN":
+      return dateFnsZhCN;
+    case "en-US":
+    default:
+      return dateFnsEnUS;
+  }
+}
+
+export function formatTimeAgo(date: Date | string | number, locale?: Locale) {
+  const effectiveLocale =
+    locale ??
+    (getLocaleFromCookie() as Locale | null) ??
+    // Fallback when cookie is missing (or on first render)
+    detectLocale();
   return formatDistanceToNow(date, {
     addSuffix: true,
+    locale: getDateFnsLocale(effectiveLocale),
   });
 }