style(chat): update message bubble max-width constraint

- Change message bubble max-width from `rb:max-w-100` to `rb:max-w-[520px]`
- Improve message content layout consistency and readability
- Ensure proper text wrapping behavior for longer messages

web/src/components/Chat/ChatContent.tsx

@@ -55,7 +55,7 @@ const ChatContent: FC<ChatContentProps> = ({
                   </div>
                 }
                 {/* 消息气泡框 */}
-                <div className={clsx('rb:border rb:text-left rb:rounded-lg rb:mt-1.5 rb:leading-4.5 rb:p-[10px_12px_2px_12px] rb:inline-block rb:max-w-100 rb:wrap-break-word', contentClassNames, {
+                <div className={clsx('rb:border rb:text-left rb:rounded-lg rb:mt-1.5 rb:leading-4.5 rb:p-[10px_12px_2px_12px] rb:inline-block rb:max-w-[520px] rb:wrap-break-word', contentClassNames, {
                   // 错误消息样式（内容为null且非助手消息）
                   'rb:border-[rgba(255,93,52,0.30)] rb:bg-[rgba(255,93,52,0.08)] rb:text-[#FF5D34]': errorDesc && item.role === 'assistant' && item.content === null,
                   // 助手消息样式