dsh-find-skill: Integrating skills search, installation, and lifecycle for DSH

`dsh-find-skill` is an MIT-licensed plugin for DeepSeek Harness (DSH) (v0.2.1) designed to bridge the `vercel-labs/skills` ecosystem, providing LLM-driven skill search, installation, and lifecycle management. The plugin supports three scopes: temporary, project, and global. Temporary skills are visible only within the current session and are automatically cleaned up upon session destruction; project or global skills are persisted to the hosted root directory. Core features include `skill_find` (searching based on the `skills.sh` API), `skill_install` (isolated installation via CLI), and `skill_remove`, along with a `/skill` subcommand for manual maintenance. Configuration options include the search base URL, default scope, and Provider ranking.