feat(i18n): 增强管理端多语言支持，优化语言初始化与恢复逻辑

src/i18n/index.ts

@@ -3,7 +3,13 @@
 import i18n from "i18next";
 import { initReactI18next } from "react-i18next";
 
-import { adminHtmlLang, applyAdminUiLocale, type AdminApiLocale } from "@/lib/admin-locale";
+import {
+  adminHtmlLang,
+  applyAdminUiLocale,
+  getStoredAdminUiLocale,
+  hydrateAdminUiLocale,
+  type AdminApiLocale,
+} from "@/lib/admin-locale";
 import enAudit from "@/i18n/locales/en/audit.json";
 import enAdminUsers from "@/i18n/locales/en/adminUsers.json";
 import enAuth from "@/i18n/locales/en/auth.json";
@@ -118,10 +124,15 @@ export function normalizeAdminLanguage(lang: string | undefined): AdminLanguage
 }
 
 function getInitialAdminLanguage(): AdminLanguage {
-  if (typeof document === "undefined") {
+  if (typeof window === "undefined") {
     return ADMIN_DEFAULT_LANGUAGE;
   }
 
+  const stored = getStoredAdminUiLocale();
+  if (stored) {
+    return stored;
+  }
+
   return normalizeAdminLanguage(document.documentElement.lang);
 }
 
@@ -133,11 +144,17 @@ function syncAdminLanguage(lang: AdminLanguage): void {
 }
 
 if (!i18n.isInitialized) {
+  if (typeof window !== "undefined") {
+    hydrateAdminUiLocale();
+  }
+
+  const initialLanguage = getInitialAdminLanguage();
+
   void i18n
     .use(initReactI18next)
     .init({
       resources,
-      lng: getInitialAdminLanguage(),
+      lng: initialLanguage,
       fallbackLng: ADMIN_DEFAULT_LANGUAGE,
       supportedLngs: [...ADMIN_SUPPORTED_LANGUAGES],
       defaultNS: "common",
@@ -149,9 +166,16 @@ if (!i18n.isInitialized) {
       react: {
         useSuspense: false,
       },
+    })
+    .then(() => {
+      const lang = getInitialAdminLanguage();
+      if (normalizeAdminLanguage(i18n.language) !== lang) {
+        void i18n.changeLanguage(lang);
+      }
+      syncAdminLanguage(normalizeAdminLanguage(i18n.resolvedLanguage ?? i18n.language));
     });
 
-  syncAdminLanguage(normalizeAdminLanguage(i18n.resolvedLanguage ?? i18n.language));
+  syncAdminLanguage(initialLanguage);
   i18n.on("languageChanged", (lang) => {
     syncAdminLanguage(normalizeAdminLanguage(lang));
   });