refactor: 移除语言切换按钮

chrome.i18n 语言由浏览器设置决定，不支持运行时切换，移除 TopBar 中的语言切换按钮及相关逻辑。

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

components/TopBar.tsx

@@ -2,7 +2,6 @@ import React, { useEffect, useMemo, useRef, useState } from 'react';
 import {
   ArrowLeft,
   ExternalLink,
-  Globe,
   History,
   Monitor,
   Moon,
@@ -17,7 +16,6 @@ import { FeatureConfig, FEATURES } from '@/config/features';
 import { storageUtil } from '@/utils/chromeStorage';
 import { openExtensionPage } from '@/utils/chromeTabs';
 import { useI18n } from '@/utils/chromeI18n';
-import { normalizeLanguage, SUPPORTED_LANGUAGES } from '@/utils/chromeI18n';
 import { cn } from '@/lib/utils'; // 1. 引入 shadcn 核心工具函数
 
 // 常量配置抽取（无需写在全局变量或 styles 对象里）
@@ -27,7 +25,7 @@ const SEARCH_HISTORY_DISPLAY = 5;
 export default function TopBar({ onOpenOptions }: { onOpenOptions: () => void }) {
   const { currentPage, goBack, navigateTo } = useRouter();
   const { mode, setMode } = useThemeMode();
-  const { t, i18n } = useI18n(['common', 'features']);
+  const { t } = useI18n(['common', 'features']);
 
   const [searchQuery, setSearchQuery] = useState('');
   const [showResults, setShowResults] = useState(false);
@@ -99,14 +97,6 @@ export default function TopBar({ onOpenOptions }: { onOpenOptions: () => void })
     setShowResults(false);
   };
 
-  const toggleLanguage = async () => {
-    const currentLng = normalizeLanguage(i18n.language);
-    const currentIndex = SUPPORTED_LANGUAGES.indexOf(currentLng);
-    const nextLng = SUPPORTED_LANGUAGES[(currentIndex + 1) % SUPPORTED_LANGUAGES.length];
-    await i18n.changeLanguage(nextLng);
-    await storageUtil.set('app/language', nextLng);
-  };
-
   const cycleThemeMode = () => {
     const nextMap = { light: 'dark', dark: 'system', system: 'light' } as const;
     setMode(nextMap[mode]);
@@ -272,9 +262,6 @@ export default function TopBar({ onOpenOptions }: { onOpenOptions: () => void })
 
       {/* 右侧：操作区 */}
       <div className="flex items-center gap-1 shrink-0">
-        <IconButton onClick={toggleLanguage} title={t('common:buttons.toggleLanguage')}>
-          <Globe className="h-4 w-4" />
-        </IconButton>
         <IconButton onClick={cycleThemeMode} title={t(`common:buttons.themeMode.${mode}`)}>
           <ThemeIcon className="h-4 w-4" />
         </IconButton>