feat: 支持多语言提示词本地化和界面优化

- 添加 prompt_locale 参数支持简体中文、繁体中文和英文提示词本地化
- 移除内置 agents 配置以简化系统架构
- 更新 ContextBuilder 使用动态提示词模板而非硬编码内容
- 在 AgentLoop、Web 接口和 AgentService 中传递 locale 参数
- 添加输出语言指令确保用户界面内容按指定语言生成
- 扩展前端 LanguageSwitcher 组件支持三种语言选项
- 优化 Header 和侧边栏组件的响应式布局和文本截断处理
- 更新测试用例验证不同语言环境下的提示词正确性

app-instance/frontend/components/LanguageSwitcher.tsx

@@ -2,40 +2,49 @@
 
 import { Languages } from 'lucide-react';
 
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from '@/components/ui/select';
+import type { AppLocale } from '@/lib/i18n/core';
+import { pickAppText } from '@/lib/i18n/core';
 import { useAppI18n } from '@/lib/i18n/provider';
 import { cn } from '@/lib/utils';
 
 const OPTIONS = [
-  { value: 'zh-CN', label: 'ZH' },
-  { value: 'en-US', label: 'EN' },
+  { value: 'zh-CN', label: '中文', shortLabel: '中' },
+  { value: 'en-US', label: 'English', shortLabel: 'EN' },
+  { value: 'zh-Hant', label: '繁體中文', shortLabel: '繁' },
 ] as const;
 
 export function LanguageSwitcher({ className }: { className?: string }) {
   const { locale, setLocale } = useAppI18n();
+  const selectedOption = OPTIONS.find((option) => option.value === locale) ?? OPTIONS[0];
 
   return (
-    <div
-      className={cn(
-        'inline-flex items-center gap-1 rounded-md border border-border bg-muted/30 p-1',
-        className
-      )}
-    >
-      <Languages className="h-3.5 w-3.5 text-muted-foreground" />
-      {OPTIONS.map((option) => (
-        <button
-          key={option.value}
-          type="button"
-          onClick={() => setLocale(option.value)}
-          className={cn(
-            'h-11 w-11 rounded text-xs font-medium transition-colors',
-            locale === option.value
-              ? 'bg-background text-foreground shadow-sm'
-              : 'text-muted-foreground hover:text-foreground'
-          )}
-        >
-          {option.label}
-        </button>
-      ))}
-    </div>
+    <Select value={locale} onValueChange={(value) => setLocale(value as AppLocale)}>
+      <SelectTrigger
+        className={cn('h-11 w-[92px] gap-1.5 bg-muted/30 px-2 sm:w-[138px] sm:gap-2 sm:px-3', className)}
+        aria-label={pickAppText(locale, '选择语言', 'Select language')}
+      >
+        <Languages className="h-3.5 w-3.5 shrink-0 text-muted-foreground" />
+        <SelectValue aria-label={selectedOption.label}>
+          <span className="min-w-0 flex-1 truncate text-left">
+            <span className="sm:hidden">{selectedOption.shortLabel}</span>
+            <span className="hidden sm:inline">{selectedOption.label}</span>
+          </span>
+        </SelectValue>
+      </SelectTrigger>
+      <SelectContent align="end">
+        {OPTIONS.map((option) => (
+          <SelectItem key={option.value} value={option.value}>
+            {option.label}
+          </SelectItem>
+        ))}
+      </SelectContent>
+    </Select>
   );
 }