feat(data-management): 添加Office文档预览功能

- 集成LibreOffice转换器实现DOC/DOCX转PDF功能
- 新增DatasetFilePreviewService处理预览文件管理
- 新增DatasetFilePreviewAsyncService异步转换任务
- 在文件删除时同步清理预览文件
- 前端实现Office文档预览状态轮询机制
- 添加预览API接口支持状态查询和转换触发
- 优化文件预览界面显示转换进度和错误信息

frontend/src/pages/DataManagement/Detail/components/Overview.tsx

@@ -1,12 +1,13 @@
-import {
-  App,
-  Button,
-  Descriptions,
-  DescriptionsProps,
-  Modal,
-  Table,
-  Input,
-} from "antd";
+import {
+  App,
+  Button,
+  Descriptions,
+  DescriptionsProps,
+  Modal,
+  Spin,
+  Table,
+  Input,
+} from "antd";
 import { formatBytes, formatDateTime } from "@/utils/unit";
 import { Download, Trash2, Folder, File } from "lucide-react";
 import { datasetTypeMap } from "../../dataset.const";
@@ -49,10 +50,12 @@ export default function Overview({
     previewVisible,
     previewFileName,
     previewContent,
-    previewFileType,
-    previewMediaUrl,
-    previewLoading,
-    closePreview,
+    previewFileType,
+    previewMediaUrl,
+    previewLoading,
+    officePreviewStatus,
+    officePreviewError,
+    closePreview,
     handleDeleteFile,
     handleDownloadFile,
     handleBatchDeleteFiles,
@@ -446,13 +449,41 @@ export default function Overview({
             />
           </div>
         )}
-        {previewFileType === "pdf" && (
-          <iframe
-            src={previewMediaUrl}
-            title={previewFileName || "PDF 预览"}
-            style={{ width: "100%", height: `${PREVIEW_MAX_HEIGHT}px`, border: "none" }}
-          />
-        )}
+        {previewFileType === "pdf" && (
+          <>
+            {previewMediaUrl ? (
+              <iframe
+                src={previewMediaUrl}
+                title={previewFileName || "PDF 预览"}
+                style={{ width: "100%", height: `${PREVIEW_MAX_HEIGHT}px`, border: "none" }}
+              />
+            ) : (
+              <div
+                style={{
+                  height: `${PREVIEW_MAX_HEIGHT}px`,
+                  display: "flex",
+                  flexDirection: "column",
+                  alignItems: "center",
+                  justifyContent: "center",
+                  gap: 12,
+                  color: "#666",
+                }}
+              >
+                {officePreviewStatus === "FAILED" ? (
+                  <>
+                    <div>转换失败</div>
+                    <div>{officePreviewError || "请稍后重试"}</div>
+                  </>
+                ) : (
+                  <>
+                    <Spin />
+                    <div>正在转换，请稍候...</div>
+                  </>
+                )}
+              </div>
+            )}
+          </>
+        )}
         {previewFileType === "video" && (
           <div style={{ textAlign: "center" }}>
             <video