dsh-project-sources: Mount multiple project directories to a workspace

This is the DSH workflow plugin maintained by yanguohong1. It mounts multiple directories outside the workspace into a single session, assigning a short alias to each directory for the model to reference absolute paths. The session's current working directory (cwd) remains the workspace, and each source inherits the same read, write, and execute permissions. It supports cross-source @ menu searches and skills discovery within sources, without requiring additional tools. **Installation:** Web UI: Settings → Plugins → Add and paste `dsh-project-sources`, or CLI: `dsh plugin --profile <profile> add dsh-project-sources@0.1.0`. **Requirements:** DSH 0.2.1-rc.5 or higher, Node.js 20+. **Notes:** Each command has only one writable root; the absolute workdir inside the source must be provided. It cannot coexist with plugins intercepting the same tool pipeline. **License:** MIT.