feat(knowledge): 添加知识条目文件上传和下载功能

- 新增文件上传接口支持批量上传知识条目文件
- 实现文件存储路径管理和安全验证机制
- 添加文件下载功能支持知识条目文件导出
- 扩展知识内容类型枚举增加FILE类型
- 扩展知识来源类型枚举增加FILE_UPLOAD类型
- 新增上传请求DTO定义文件验证和元数据配置
- 实现文件上传目录管理和文件名安全处理
- 添加文件扩展名识别和内容类型转换逻辑

frontend/src/pages/KnowledgeManagement/Detail/KnowledgeSetDetail.tsx

@@ -19,12 +19,14 @@ import useFetchData from "@/hooks/useFetchData";
 import {
   deleteKnowledgeItemByIdUsingDelete,
   deleteKnowledgeSetByIdUsingDelete,
+  downloadKnowledgeItemFileUsingGet,
   exportKnowledgeItemsUsingGet,
   queryKnowledgeItemsUsingGet,
   queryKnowledgeSetByIdUsingGet,
 } from "../knowledge-management.api";
 import {
   knowledgeContentTypeOptions,
+  knowledgeSourceTypeOptions,
   knowledgeStatusMap,
   mapKnowledgeItem,
   KnowledgeItemView,
@@ -33,6 +35,7 @@ import {
   KnowledgeItem,
   KnowledgeSet,
   KnowledgeContentType,
+  KnowledgeSourceType,
   KnowledgeStatusType,
 } from "../knowledge-management.model";
 import CreateKnowledgeSet from "../components/CreateKnowledgeSet";
@@ -108,6 +111,12 @@ const KnowledgeSetDetail = () => {
   };
 
   const isReadableItem = (record: KnowledgeItemView) => {
+    if (
+      record.contentType === KnowledgeContentType.FILE ||
+      record.sourceType === KnowledgeSourceType.FILE_UPLOAD
+    ) {
+      return false;
+    }
     return (
       record.contentType === KnowledgeContentType.TEXT ||
       record.contentType === KnowledgeContentType.MARKDOWN
@@ -115,6 +124,13 @@ const KnowledgeSetDetail = () => {
   };
 
   const handleReadItem = async (record: KnowledgeItemView) => {
+    if (
+      record.contentType === KnowledgeContentType.FILE ||
+      record.sourceType === KnowledgeSourceType.FILE_UPLOAD
+    ) {
+      message.info("该条目为文件，请使用下载查看");
+      return;
+    }
     setReadItemId(record.id);
     setReadTitle(record.title || "知识条目");
 
@@ -156,6 +172,16 @@ const KnowledgeSetDetail = () => {
     }
   };
 
+  const handleDownloadItem = async (record: KnowledgeItemView) => {
+    if (!id) return;
+    try {
+      await downloadKnowledgeItemFileUsingGet(id, record.id, record.sourceFileId);
+    } catch (error) {
+      console.error("下载知识条目文件失败", error);
+      message.error("下载失败，请稍后重试");
+    }
+  };
+
   const statusMeta = knowledgeSet?.status
     ? knowledgeStatusMap[knowledgeSet.status]
     : undefined;
@@ -218,6 +244,10 @@ const KnowledgeSetDetail = () => {
       key: "sourceType",
       width: 140,
       ellipsis: true,
+      render: (sourceType: string) =>
+        knowledgeSourceTypeOptions.find((opt) => opt.value === sourceType)?.label ||
+        sourceType ||
+        "-",
     },
     {
       title: "更新时间",
@@ -232,16 +262,28 @@ const KnowledgeSetDetail = () => {
       width: 200,
       render: (_: unknown, record: KnowledgeItemView) => (
         <div className="flex items-center gap-2">
-          <Tooltip title="阅读">
-            <Button
-              type="text"
-              icon={<EyeOutlined />}
-              onClick={() => handleReadItem(record)}
-              disabled={!isReadableItem(record)}
-              loading={readItemId === record.id}
-              aria-label="阅读"
-            />
-          </Tooltip>
+          {isReadableItem(record) && (
+            <Tooltip title="阅读">
+              <Button
+                type="text"
+                icon={<EyeOutlined />}
+                onClick={() => handleReadItem(record)}
+                loading={readItemId === record.id}
+                aria-label="阅读"
+              />
+            </Tooltip>
+          )}
+          {(record.contentType === KnowledgeContentType.FILE ||
+            record.sourceType === KnowledgeSourceType.FILE_UPLOAD) && (
+            <Tooltip title="下载文件">
+              <Button
+                type="text"
+                icon={<DownloadOutlined />}
+                onClick={() => handleDownloadItem(record)}
+                aria-label="下载文件"
+              />
+            </Tooltip>
+          )}
           <Button
             type="text"
             icon={<EditOutlined />}