dsh-secure-remote: DeepSeek Harness SSH Security and Stability Plugin

`dsh-secure-remote` is an SSH plugin for DeepSeek Harness that replaces the native provider through a bundle patch without requiring source code modifications. Its core features include fixing macOS/Linux `ControlPath` issues caused by overly long paths, disabling reconnection on Windows, securely storing passwords via the DSH service, strictly limiting remote file operation boundaries, and enabling host key verification by default. The plugin supports key/password authentication and is compatible with the existing architecture, though it does not yet support remote Windows environments or advanced file transfer features.