feat: 添加download路由用于展示文档信息

- 添加/download/documentID路由用于文档下载
- server端添加文档元数据获取与下载API
- 将app中的types移至shared，与server共享

shared/types/file.ts

@@ -0,0 +1,12 @@
+export interface FileMeta {
+  id: string;
+  title: string;
+  filename_download: string;
+  type: string;
+  filesize: number;
+  width?: number;
+  height?: number;
+  uploaded_on?: string;
+  url: string;
+  previewable: boolean;
+}