dsh-bao: Add a long-term memory assistant plugin to DeepSeek Harness

DSH-Bao (DSH 宝) is a DSH plugin maintained by milestone-17, packaging cross-session long-term memory, dedicated Assistant Agent presets, daily briefs, desktop notifications, and a work status overview panel into a workflow of "Assistant proactively reaches out." Memory is written to `$DSH_HOME/bao/memory.json` and injected as dynamic runtime context via system-prompt into every request, coexisting with the `complete:true` preset persona; notifications fall back in order to Electron and Windows toast. It does not replace DSH's native `schedule_*/notify_user/goals` primitives but rather combines them into a productized outer layer. The end of the article provides the plugin marketplace command, Discover index address, local directory installation, manual mounting of `cordis.patch.yml`, and the complete configuration table.