新增通用聊天图片预览组件

- ImagePreview / ChatImage：全屏预览、ESC 关闭、下载
- 接入工作台、访客 Widget、对话记录

web/src/widgets/VisitorChat.tsx

@@ -4,6 +4,7 @@ import {
   StarFilled, MinusOutlined, PictureOutlined, CustomerServiceOutlined,
 } from '@ant-design/icons'
 import EmojiPicker, { insertAtCursor } from '@/components/common/EmojiPicker'
+import { ChatImage } from '@/components/common/ImagePreview'
 
 interface Message {
   id: number
@@ -468,7 +469,7 @@ const VisitorChat = ({
             <div key={msg.id} className="flex justify-end max-w-[85%] ml-auto">
               <div className={`rounded-xl bg-[#2563eb] text-white text-[13px] leading-normal ${msg.type === 'image' ? 'p-1.5' : 'px-4 py-3'}`}>
                 {msg.type === 'image' ? (
-                  <img src={msg.content} alt="图片" className="max-w-[180px] rounded-lg block" />
+                  <ChatImage src={msg.content} alt="图片" className="max-w-[180px] max-h-[180px]" />
                 ) : (
                   <p className="m-0 whitespace-pre-wrap break-words">{msg.content}</p>
                 )}
@@ -481,7 +482,7 @@ const VisitorChat = ({
               </div>
               <div className={`rounded-xl bg-white border border-neutral-200 text-[13px] text-neutral-800 leading-normal ${msg.type === 'image' ? 'p-1.5' : 'px-4 py-3'}`}>
                 {msg.type === 'image' ? (
-                  <img src={msg.content} alt="图片" className="max-w-[180px] rounded-lg block" />
+                  <ChatImage src={msg.content} alt="图片" className="max-w-[180px] max-h-[180px]" />
                 ) : (
                   <p className="m-0 whitespace-pre-wrap break-words">{msg.content}</p>
                 )}