feat(remote): 文件传输改用Electron IPC通道

- 主进程新增4个IPC handler处理远程文件操作
- 前端通过IPC调用而非浏览器fetch访问远程API
- Remote服务新增3003端口专门处理文件传输
- 上传使用文件路径方案，下载使用保存对话框方案

src/types/electron.d.ts

@@ -16,6 +16,26 @@ export interface ElectronAPI {
   onRemoteClipboardAutoSync: (callback: (text: string) => void) => () => void
   clipboardReadText: () => Promise<{ success: boolean; text?: string; error?: string }>
   clipboardWriteText: (text: string) => Promise<{ success: boolean; error?: string }>
+  remoteFetchDrives: (serverHost: string, port: number, password?: string) => Promise<{
+    success: boolean
+    data?: Array<{ name: string; path: string; type: 'file' | 'dir'; size: number; modified: string }>
+    error?: string
+  }>
+  remoteFetchFiles: (serverHost: string, port: number, filePath: string, password?: string) => Promise<{
+    success: boolean
+    data?: Array<{ name: string; path: string; type: 'file' | 'dir'; size: number; modified?: string }>
+    error?: string
+  }>
+  remoteUploadFile: (serverHost: string, port: number, filePath: string, remotePath: string, password?: string) => Promise<{
+    success: boolean
+    error?: string
+  }>
+  remoteDownloadFile: (serverHost: string, port: number, fileName: string, remotePath: string, password?: string) => Promise<{
+    success: boolean
+    filePath?: string
+    error?: string
+    canceled?: boolean
+  }>
 }
 
 declare global {