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/oss-transport.ts

@@ -5,6 +5,7 @@
 import type {
   FsTransport, FileItem, FileOperationResult, DetectTypeResult,
 } from './transport'
+import { transformFileList, joinPath, probeAlive } from './transport'
 import type { ConnectionProfile } from './connection-manager'
 import {
   OssConnect, OssDisconnect, OssListDir, OssReadFile,
@@ -13,14 +14,6 @@ import {
   OssGetCommonPaths, OssWriteBase64File, OssGetSignedURL,
 } 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 OssTransport implements FsTransport {
   private profile: ConnectionProfile
   private connID: string | null = null
@@ -40,6 +33,10 @@ export class OssTransport implements FsTransport {
     return result
   }
 
+  async isAlive(): Promise<boolean> {
+    return probeAlive(this.connID, id => OssListDir(id, ''))
+  }
+
   get sessionId(): string | null { return this.connID }
 
   async disconnect(): Promise<void> {
@@ -84,13 +81,11 @@ export class OssTransport implements FsTransport {
   // ====== 文件操作 ======
 
   async createFile(dirPath: string, filename: string): Promise<FileOperationResult> {
-    const fullPath = dirPath.replace(/\/$/, '') + '/' + filename
-    return OssCreateFile(this.requireConn(), fullPath)
+    return OssCreateFile(this.requireConn(), joinPath(dirPath, filename))
   }
 
   async createDir(parentPath: string, dirname: string): Promise<FileOperationResult> {
-    const fullPath = parentPath.replace(/\/$/, '') + '/' + dirname
-    return OssCreateDir(this.requireConn(), fullPath)
+    return OssCreateDir(this.requireConn(), joinPath(parentPath, dirname))
   }
 
   async deletePath(path: string): Promise<FileOperationResult> {
@@ -105,6 +100,24 @@ export class OssTransport implements FsTransport {
     })
   }
 
+  // ====== 复制/移动/传输（不支持）======
+
+  async copyPath(_src: string, _dst: string): Promise<void> {
+    throw new Error('OSS 面板暂不支持复制/粘贴')
+  }
+
+  async movePath(_src: string, _dst: string): Promise<void> {
+    throw new Error('OSS 面板暂不支持剪切/粘贴')
+  }
+
+  async downloadToFile(_path: string, _localDstDir: string): Promise<string> {
+    throw new Error('OSS 下载到本机暂未实现')
+  }
+
+  async uploadFromFile(_localPath: string, _remoteDir: string): Promise<void> {
+    throw new Error('OSS 上传暂未实现')
+  }
+
   // ====== ZIP 操作（不支持）======
 
   async listZipContents(_zipPath: string): Promise<FileItem[]> {
@@ -177,4 +190,7 @@ export class OssTransport implements FsTransport {
   async getSignedUrl(key: string): Promise<string> {
     return OssGetSignedURL(this.requireConn(), key)
   }
+
+  async watchFile(_path: string): Promise<void> { /* OSS 模式不支持文件监听 */ }
+  async unwatchFile(): Promise<void> { /* OSS 模式不支持文件监听 */ }
 }