feat(任务全景): 流转树改为宽屏弹窗并放大字体

- TaskFlowView 增加 size prop(sm默认/lg放大)，弹窗模式卡片/字体/按钮全部放大
- TaskTreeViewer 通用 Modal 导出并支持 widthClass/bodyClassName 定制
- AdminTasksPage 内嵌展开改为宽屏 Modal(max-w-6xl)，保留接收/转交/驳回操作
- 记录弹窗放大且 z-index 提升到 z-[60] 保证覆盖弹窗
- 修复 TaskRecordResponse 无 note 字段的类型错误，清理未使用 import

frontend/src/components/TaskTree/TaskTreeViewer.tsx

@@ -25,16 +25,20 @@ import { getStatusConfig } from "../../constants/task";
 // 通用 Modal 容器
 // ============================================================
 
-const Modal = memo(function Modal({
+export const Modal = memo(function Modal({
   open,
   onClose,
   title,
   children,
+  widthClass = "max-w-md",
+  bodyClassName = "",
 }: {
   open: boolean;
   onClose: () => void;
   title: string;
   children: React.ReactNode;
+  widthClass?: string;
+  bodyClassName?: string;
 }) {
   if (!open) return null;
 
@@ -46,7 +50,7 @@ const Modal = memo(function Modal({
         onClick={onClose}
       />
       {/* 弹窗 */}
-      <div className="relative z-10 mx-4 w-full max-w-md rounded-xl bg-white p-6 shadow-2xl">
+      <div className={`relative z-10 mx-4 w-full ${widthClass} rounded-xl bg-white p-6 shadow-2xl ${bodyClassName}`}>
         <div className="mb-4 flex items-center justify-between">
           <h3 className="text-base font-bold text-gray-800">{title}</h3>
           <button