dsh-im-companion: Enhancing dsh-im with Assistant and Home

DSH `dsh-im-companion` is a companion plugin built on top of DSH, designed to optimize multi-workspace management and assistant tracking. It mitigates high migration costs through enhanced views, status indicators, and a “move” feature. Core features include workspace filtering, Agent detail views, Fleet Radar, and light theme support. Installation requires `dsh-im`; the plugin can be installed and enabled via npm to enhance the user experience.