feat(frontend): 控制台 next-intl 中英双语

接入无 URL 前缀的 zh-CN/en，顶栏与外观设置可切换语言；选择写入 cookie 后刷新生效。

frontend/app/(main)/websites/components/website-utils.ts

@@ -9,8 +9,15 @@ import type { FileImportFormValues, ManualImportFormValues } from './schemas';
 
 export type StatusTone = 'success' | 'warning' | 'danger' | 'info';
 
-export function getErrorMessage(error: unknown) {
-  return error instanceof Error ? error.message : '请求失败，请稍后重试。';
+export type TranslateFn = (
+  key: string,
+  values?: Record<string, string | number>,
+) => string;
+
+export function getErrorMessage(error: unknown, fallback?: string) {
+  return error instanceof Error
+    ? error.message
+    : (fallback ?? '请求失败，请稍后重试。');
 }
 
 export function getMatchTypeMeta(domain: string): {
@@ -22,7 +29,10 @@ export function getMatchTypeMeta(domain: string): {
     : { label: '精确匹配', tone: 'info' };
 }
 
-export function getCertificateStatus(certificate: TlsCertificateItem): {
+export function getCertificateStatus(
+  certificate: TlsCertificateItem,
+  t: TranslateFn,
+): {
   label: string;
   tone: StatusTone;
 } {
@@ -31,18 +41,18 @@ export function getCertificateStatus(certificate: TlsCertificateItem): {
   const days = Math.ceil(diffMs / (1000 * 60 * 60 * 24));
 
   if (Number.isNaN(expiresAt)) {
-    return { label: '有效期未知', tone: 'warning' };
+    return { label: t('certStatus.unknownExpiry'), tone: 'warning' };
   }
 
   if (days < 0) {
-    return { label: '已过期', tone: 'danger' };
+    return { label: t('certStatus.expired'), tone: 'danger' };
   }
 
   if (days <= 30) {
-    return { label: `${days} 天内到期`, tone: 'warning' };
+    return { label: t('certStatus.expiresInDays', { days }), tone: 'warning' };
   }
 
-  return { label: '有效', tone: 'success' };
+  return { label: t('certStatus.valid'), tone: 'success' };
 }
 
 export function buildCertificateLabel(certificate: TlsCertificateItem) {
@@ -66,9 +76,10 @@ export function toFilePayload(
   values: FileImportFormValues,
   certFile: File | null,
   keyFile: File | null,
+  missingFilesMessage: string,
 ): TlsCertificateFileImportPayload {
   if (!certFile || !keyFile) {
-    throw new Error('请选择证书文件和私钥文件。');
+    throw new Error(missingFilesMessage);
   }
 
   return {