dsh-agent-registry: DeepSeek Harness Workspace Agent Registration

`dsh-agent-registry` is a Phase 0 plugin in the DeepSeek Harness ecosystem, designed to govern interactions between workspaces and agents and address mutual interference between sessions and presets. Through a “binding and partitioning” mechanism, it associates a DSH workspace with a specific Claw Agent and isolates presets to prevent sessions from misusing official presets. Users can manage scope permissions (default: read-only) and models in the plugin settings. Removing a binding is equivalent to archiving it; the project directory must be handled first before uninstalling. The plugin is MIT licensed and lays the foundation for future permission control and isolation.