fix: 修正 markdown-to-jsx 导入方式 + 新增 formatDateLabel 日期工具函数

- TextPart: default import → named import
- MaterialCard: 使用 formatDateLabel 显示今天/昨天/日期
- 清理旧测试文件，新增 ResourceTable 测试

src/web/features/chat/parts/TextPart.tsx

@@ -1,5 +1,5 @@
 import { Typography } from "antd";
-import Markdown from "markdown-to-jsx/react";
+import { Markdown } from "markdown-to-jsx/react";
 
 import type { PartProps } from "./types";
 

src/web/features/inbox/components/MaterialCard.tsx

@@ -3,6 +3,8 @@ import { Button, Flex, Popconfirm, Tag, Typography } from "antd";
 
 import type { Material, MaterialStatus } from "../types";
 
+import { formatDateLabel } from "../../../shared/utils/time";
+
 interface MaterialCardProps {
   material: Material;
   onDelete: () => void;
@@ -12,7 +14,7 @@ interface MaterialCardProps {
 
 function formatAssociatedDate(date: string): string {
   if (!date) return "—";
-  return date;
+  return formatDateLabel(date);
 }
 
 const STATUS_MAP: Record<MaterialStatus, { color: string; label: string }> = {