cslht11/dsh-ssh-remote: SSH Remote Workspace Plugin for DSH

`cslht11/dsh-ssh-remote` is an SSH remote workspace plugin for DeepSeek Harness (DSH), derived from `flymysql/dsh-remote` (v0.6.0, MIT License). This plugin solves the problem of manually switching SSH connections when handling files on multiple remote servers within an Agent, supporting parallel registration of multiple machines, independent connection pools, and switching between the current machine. Core features include: 1. **Multi-machine Management**: Supports registering an arbitrary number of servers, configuring host, port, password, or keys, with configurations saved in a local JSON file. 2. **Remote Workspace**: Specifies a remote directory for each machine and provides a bidirectional SFTP synchronization mechanism (`rw_sync` pull, `rw_push` push).