dsh-chess-plan: Chess Practice Planning

The DeepSeek Harness (DSH) plugin `dsh-chess-plan` is specifically designed for generating chess learning plans. Maintained by the developer `uckkk`, it requires no internet connection and is implemented in pure Node.js, providing the `chess_plan` tool. Developers can invoke it directly after installation to quickly generate structured chess practice plans, making it suitable for building teaching workflow scenarios. Since it runs with the permissions of the current process, its source code should be checked for security before use.