新增: 文件操作增强与预览扩展

- 文件剪贴板复制剪切粘贴，重名自动副本
- SFTP下载到本机与外部文件拖入，目录递归
- 传输进度浮动面板，transfer-progress事件链
- Drawio预览，Excel工作线程，冻结看门狗
- cmd与bat自写batch语法高亮，psm1等映射补齐

frontend/src/api/sftp-transport.ts

@@ -5,22 +5,16 @@
 import type {
   FsTransport, FileItem, FileOperationResult, DetectTypeResult,
 } from './transport'
+import { transformFileList, joinPath, probeAlive } from './transport'
 import type { ConnectionProfile } from './connection-manager'
 import {
   SftpConnect, SftpDisconnect, SftpListDir, SftpReadFile,
   SftpWriteFile, SftpGetFileInfo, SftpCreateDir, SftpCreateFile,
   SftpDeletePath, SftpRenamePath, SftpDownloadToTemp, SftpDownloadSiteForPreview,
+  SftpDownloadToFile, SftpUploadFromFile,
   SftpGetCommonPaths, SftpWriteBase64File,
 } from '@bindings/u-desk/app'
 
-function transformFile(file: any): FileItem {
-  return { ...file, is_dir: file.is_dir, mod_time: file.mod_time }
-}
-
-function transformFileList(files: any[]): FileItem[] {
-  return files.map(transformFile)
-}
-
 export class SftpTransport implements FsTransport {
   private profile: ConnectionProfile
   private connID: string | null = null
@@ -42,6 +36,10 @@ export class SftpTransport implements FsTransport {
     return result
   }
 
+  async isAlive(): Promise<boolean> {
+    return probeAlive(this.connID, id => SftpGetFileInfo(id, '/'))
+  }
+
   get sessionId(): string | null { return this.connID }
 
   async disconnect(): Promise<void> {
@@ -90,13 +88,11 @@ export class SftpTransport implements FsTransport {
   // ====== 文件操作 ======
 
   async createFile(dirPath: string, filename: string): Promise<FileOperationResult> {
-    const fullPath = dirPath.replace(/\/$/, '') + '/' + filename
-    return SftpCreateFile(this.requireConn(), fullPath)
+    return SftpCreateFile(this.requireConn(), joinPath(dirPath, filename))
   }
 
   async createDir(parentPath: string, dirname: string): Promise<FileOperationResult> {
-    const fullPath = parentPath.replace(/\/$/, '') + '/' + dirname
-    return SftpCreateDir(this.requireConn(), fullPath)
+    return SftpCreateDir(this.requireConn(), joinPath(parentPath, dirname))
   }
 
   async deletePath(path: string): Promise<FileOperationResult> {
@@ -111,6 +107,28 @@ export class SftpTransport implements FsTransport {
     })
   }
 
+  // ====== 复制/移动（粘贴仅本地面板支持）======
+
+  async copyPath(_src: string, _dst: string): Promise<void> {
+    throw new Error('SFTP 面板暂不支持粘贴，可使用拖拽上传')
+  }
+
+  async movePath(_src: string, _dst: string): Promise<void> {
+    throw new Error('SFTP 面板暂不支持粘贴，可使用拖拽上传')
+  }
+
+  // ====== 传输 ======
+
+  /** 下载远程文件/目录到用户指定目录（流式无上限，重名自动副本），返回本地落地路径 */
+  async downloadToFile(remotePath: string, localDstDir: string): Promise<string> {
+    return SftpDownloadToFile(this.requireConn(), remotePath, localDstDir)
+  }
+
+  /** 上传本地文件/目录到远程目录（流式，目录递归） */
+  async uploadFromFile(localPath: string, remoteDir: string): Promise<void> {
+    await SftpUploadFromFile(this.requireConn(), localPath, remoteDir)
+  }
+
   // ====== ZIP 操作（不支持）======
 
   async listZipContents(_zipPath: string): Promise<FileItem[]> {
@@ -179,4 +197,7 @@ export class SftpTransport implements FsTransport {
   async downloadSiteForPreview(remotePath: string): Promise<string> {
     return SftpDownloadSiteForPreview(this.requireConn(), remotePath)
   }
+
+  async watchFile(_path: string): Promise<void> { /* SFTP 模式不支持文件监听 */ }
+  async unwatchFile(): Promise<void> { /* SFTP 模式不支持文件监听 */ }
 }