feat(settings): 实现数据导出和清除聊天功能

- 添加导出聊天数据功能，支持 JSON 格式下载
- 添加清除所有聊天功能，带确认对话框
- 显示待删除对话和消息数量统计
- 优化 SettingsSection 组件支持暗色主题

src/app/settings/page.tsx

@@ -2,10 +2,11 @@
 
 import { useState, useEffect } from 'react';
 import Link from 'next/link';
-import { ArrowLeft, Download, Check, Loader2, Eye, EyeOff, RotateCcw, Moon, Sun, Sparkles, Trash2 } from 'lucide-react';
+import { ArrowLeft, Download, Check, Loader2, Eye, EyeOff, RotateCcw, Moon, Sun, Sparkles, Trash2, AlertTriangle } from 'lucide-react';
 import { Toggle } from '@/components/ui/Toggle';
 import { ModelCardSelector } from '@/components/ui/ModelCardSelector';
 import { FontSizePicker } from '@/components/ui/FontSizePicker';
+import { ConfirmDialog } from '@/components/ui/ConfirmDialog';
 import { cn } from '@/lib/utils';
 import { useSettings, useModels, useTools } from '@/hooks/useSettings';
 
@@ -59,6 +60,12 @@ export default function SettingsPage() {
   const [temperature, setTemperature] = useState('0.7');
   const [promptSaveStatus, setPromptSaveStatus] = useState<'idle' | 'saving' | 'saved' | 'error'>('idle');
 
+  // 导出和清除状态
+  const [exportLoading, setExportLoading] = useState(false);
+  const [clearDialogOpen, setClearDialogOpen] = useState(false);
+  const [clearLoading, setClearLoading] = useState(false);
+  const [chatStats, setChatStats] = useState<{ conversationCount: number; messageCount: number } | null>(null);
+
   // 当设置加载完成后，更新本地状态
   useEffect(() => {
     if (settings) {
@@ -198,6 +205,70 @@ export default function SettingsPage() {
     }
   };
 
+  // 导出聊天数据
+  const handleExportData = async () => {
+    setExportLoading(true);
+    try {
+      const response = await fetch('/api/conversations/export');
+      if (!response.ok) {
+        throw new Error('Export failed');
+      }
+      const data = await response.json();
+
+      // 创建 Blob 并下载
+      const blob = new Blob([JSON.stringify(data, null, 2)], { type: 'application/json' });
+      const url = URL.createObjectURL(blob);
+      const a = document.createElement('a');
+      a.href = url;
+      const date = new Date().toISOString().split('T')[0];
+      a.download = `cchcode-chat-export-${date}.json`;
+      document.body.appendChild(a);
+      a.click();
+      document.body.removeChild(a);
+      URL.revokeObjectURL(url);
+    } catch (error) {
+      console.error('Failed to export data:', error);
+      alert('导出失败，请稍后重试');
+    } finally {
+      setExportLoading(false);
+    }
+  };
+
+  // 打开清除对话框（获取统计信息）
+  const handleOpenClearDialog = async () => {
+    try {
+      const response = await fetch('/api/conversations/all');
+      if (response.ok) {
+        const stats = await response.json();
+        setChatStats(stats);
+      }
+    } catch (error) {
+      console.error('Failed to get stats:', error);
+    }
+    setClearDialogOpen(true);
+  };
+
+  // 清除所有聊天
+  const handleClearAllChats = async () => {
+    setClearLoading(true);
+    try {
+      const response = await fetch('/api/conversations/all', {
+        method: 'DELETE',
+      });
+      if (!response.ok) {
+        throw new Error('Delete failed');
+      }
+      setClearDialogOpen(false);
+      // 跳转到首页
+      window.location.href = '/';
+    } catch (error) {
+      console.error('Failed to clear chats:', error);
+      alert('清除失败，请稍后重试');
+    } finally {
+      setClearLoading(false);
+    }
+  };
+
   if (loading) {
     return (
       <div className="flex min-h-screen items-center justify-center">
@@ -510,9 +581,17 @@ export default function SettingsPage() {
                 label="导出数据"
                 description="下载所有聊天历史"
               >
-                <button className="btn-ghost inline-flex items-center gap-2">
+                <button
-                  <Download size={16} />
+                  onClick={handleExportData}
-                  导出
+                  disabled={exportLoading}
+                  className="btn-ghost inline-flex items-center gap-2"
+                >
+                  {exportLoading ? (
+                    <Loader2 size={16} className="animate-spin" />
+                  ) : (
+                    <Download size={16} />
+                  )}
+                  {exportLoading ? '导出中...' : '导出'}
                 </button>
               </SettingsItem>
 
@@ -520,12 +599,49 @@ export default function SettingsPage() {
                 label="清除所有聊天"
                 description="删除所有对话历史"
               >
-                <button className="btn-ghost text-red-600 hover:text-red-700 inline-flex items-center gap-2">
+                <button
+                  onClick={handleOpenClearDialog}
+                  className="btn-ghost text-red-600 hover:text-red-700 inline-flex items-center gap-2"
+                >
                   <Trash2 size={16} />
                   清除
                 </button>
               </SettingsItem>
             </SettingsSection>
+
+      {/* 清除确认对话框 */}
+      <ConfirmDialog
+        isOpen={clearDialogOpen}
+        onClose={() => setClearDialogOpen(false)}
+        onConfirm={handleClearAllChats}
+        title="确认清除所有聊天记录？"
+        variant="danger"
+        confirmText="确认清除"
+        cancelText="取消"
+        loading={clearLoading}
+      >
+        <div className="space-y-3">
+          <p className="text-sm text-[var(--color-text-secondary)]">
+            此操作将永久删除：
+          </p>
+          <ul className="text-sm text-[var(--color-text-primary)] space-y-1 ml-4">
+            <li className="flex items-center gap-2">
+              <span className="w-1.5 h-1.5 rounded-full bg-red-500" />
+              <span><strong>{chatStats?.conversationCount || 0}</strong> 个对话</span>
+            </li>
+            <li className="flex items-center gap-2">
+              <span className="w-1.5 h-1.5 rounded-full bg-red-500" />
+              <span><strong>{chatStats?.messageCount || 0}</strong> 条消息</span>
+            </li>
+          </ul>
+          <div className="flex items-start gap-2 p-3 rounded-md bg-red-500/10 border border-red-500/20">
+            <AlertTriangle className="w-4 h-4 text-red-500 mt-0.5 flex-shrink-0" />
+            <p className="text-xs text-red-500">
+              此操作不可撤销！建议先导出数据备份。
+            </p>
+          </div>
+        </div>
+      </ConfirmDialog>
       </main>
     </div>
   );
@@ -543,22 +659,22 @@ function SettingsSection({ title, description, children, variant = 'default' }:
   return (
     <section
       className={cn(
-        'bg-white border rounded-md mb-6 overflow-hidden',
+        'bg-[var(--color-bg-primary)] border rounded-md mb-6 overflow-hidden',
-        variant === 'danger' ? 'border-red-200' : 'border-[var(--color-border)]'
+        variant === 'danger' ? 'border-red-500/20' : 'border-[var(--color-border)]'
       )}
     >
       <div
         className={cn(
           'px-5 py-4 border-b',
           variant === 'danger'
-            ? 'bg-red-50 border-red-200'
+            ? 'bg-red-500/10 border-red-500/20'
             : 'border-[var(--color-border-light)]'
         )}
       >
         <h2
           className={cn(
             'text-base font-semibold',
-            variant === 'danger' ? 'text-red-600' : 'text-[var(--color-text-primary)]'
+            variant === 'danger' ? 'text-red-500' : 'text-[var(--color-text-primary)]'
           )}
         >
           {title}