dsh-inst-plan: Instrument Learning Plan

dsh-inst-plan is a DeepSeek Harness (DSH) plugin maintained by uckkk, providing a lightweight local solution for generating structured learning plans for traditional musical instruments. The plugin is implemented in Node.js, has no network dependencies, and its core feature is the `inst_plan` tool. Installation requires running the specified command and depends on specific versions of `@deepseek-ai/cordis` and `@deepseek-ai/dsh-tools`. It is suitable for scenarios that require built-in domain-specific knowledge while avoiding external network calls.