feat(web): 添加全局 Toast 通知系统和资产预览导航功能

- 新增 ToastProvider 和 useToast hook，支持全局成功/错误/信息提示
- 资产预览增加左右导航按钮、键盘快捷键(方向键)和计数器显示
- 资产库增加图片/视频类型筛选标签页及计数
- 对话列表增加最近对话展示、搜索优化和删除确认
- 消息增加删除确认对话框
- 优化聊天自动滚动行为，仅在用户未手动滚动时跟随新内容
- 新增删除消息 API 端点
- 优化消息历史清理逻辑，过滤错误消息和孤儿 tool 消息
- 添加自定义滚动条样式
- 优化账户参考图显示逻辑，支持本地文件显示
- 修复对话创建流程，直接导航到新创建的对话

web/client/src/components/chat/ChatMessage.tsx

@@ -1,7 +1,8 @@
 import { useState, useCallback } from 'react';
 import { cn } from '@/lib/utils';
 import { renderMarkdown } from '@/lib/markdown';
-import { Bot, User, Copy, Trash2, ChevronDown, ChevronRight, RefreshCw, ArrowRight, Quote, Check, Brain } from 'lucide-react';
+import { Bot, User, Copy, Trash2, ChevronDown, ChevronRight, RefreshCw, ArrowRight, Quote, Brain } from 'lucide-react';
+import { useToast } from '@/hooks/useToast';
 import type { Message } from '@/types';
 
 type MessageState = 'streaming' | 'thinking' | 'done';
@@ -26,16 +27,20 @@ function getState(msg: Message, isLast: boolean, isThinking: boolean): MessageSt
 export function ChatMessage({ message, isLast, isThinking, onRegenerate, onContinue, onQuote, onDelete }: Props) {
   const isUser = message.role === 'user';
   const isTool = message.role === 'tool';
-  const [copied, setCopied] = useState(false);
   const [reasoningOpen, setReasoningOpen] = useState(false);
+  const { toast } = useToast();
   const state = getState(message, !!isLast, !!isThinking);
 
   const handleCopy = useCallback(() => {
     navigator.clipboard.writeText(message.content).then(() => {
-      setCopied(true);
-      setTimeout(() => setCopied(false), 2000);
+      toast('已复制到剪贴板', 'success');
     });
-  }, [message.content]);
+  }, [message.content, toast]);
+
+  const handleDelete = useCallback(() => {
+    if (!confirm('确定删除这条消息？')) return;
+    onDelete?.(message.id);
+  }, [message.id, onDelete]);
 
   // Tool messages
   if (isTool) {
@@ -125,13 +130,13 @@ export function ChatMessage({ message, isLast, isThinking, onRegenerate, onConti
           <div className="flex gap-0.5 mt-1 opacity-0 group-hover/msg:opacity-100 transition-opacity px-1">
             <button onClick={handleCopy}
               className="flex items-center gap-1 px-1.5 py-0.5 rounded text-[10px] text-zinc-400 hover:text-zinc-600 hover:bg-zinc-100 transition-colors">
-              {copied ? <><Check size={10} />已复制</> : <><Copy size={10} />复制</>}
+              <Copy size={10} />复制
             </button>
             <button onClick={() => onQuote?.(message.content)}
               className="flex items-center gap-1 px-1.5 py-0.5 rounded text-[10px] text-zinc-400 hover:text-zinc-600 hover:bg-zinc-100 transition-colors">
               <Quote size={10} />引用
             </button>
-            <button onClick={() => onDelete?.(message.id)}
+            <button onClick={handleDelete}
               className="flex items-center gap-1 px-1.5 py-0.5 rounded text-[10px] text-zinc-400 hover:text-red-500 hover:bg-red-50 transition-colors">
               <Trash2 size={10} />删除
             </button>