dsh-mattpocock-skills: Integrating Matt Pocock's Engineering Skills into DeepSeek Harness

`dsh-mattpocock-skills` is a plugin for DeepSeek Harness (DSH) derived from `mattpocock/skills`, containing 25 engineering and productivity skills (such as TDD, code review, and domain modeling). This plugin aims to centrally manage engineering workflows to prevent prompts from being scattered or scripts from being manually maintained. Its core features include: on-demand skill loading, where model names are exposed only when viewing the directory and content is read only upon invocation; support for explicit user invocation via `/skill-name`; verbatim preservation of content from the upstream English source, accompanied by hash checksums and a `diff` command for self-verification; and zero runtime dependencies with a lightweight installation. Installation requires using the `dsh plugin add` command to point to a GitHub or local path, requiring Node...