dsh-anywhere: Deploy the DeepSeek Harness Workspace on Any Machine

`dsh-anywhere` is a plugin for DeepSeek Harness (DSH) designed to address the challenges of operating remote machines, especially devices on internal networks or behind NAT. It uses SSH to directly turn remote machines into local workspaces and provides two modes: Fleet mode, which registers unreachable machines via network tunneling, and World mode, which treats remote devices as a filesystem and subprocess runtime. The plugin has no external dependencies, leverages OpenSSH ControlMaster to optimize performance, supports agent-native tools acting directly on remote targets, and is suitable for building cross-machine agent workflows.