dsh-anchored-preset-installer: One-Click Delivery of DSH Agent Experimental Presets

`dsh-anchored-preset-installer` is a plugin for DeepSeek Harness (DSH) designed to simplify the deployment of experimental presets (such as `dsh-anchored-standard`). It automatically writes preset directories to the user’s trusted preset root directory, eliminating the cumbersome steps associated with manual copying. The plugin supports one-click installation, runs cleanly without making any network requests, and includes a Create-only mechanism and fault isolation to ensure that users’ existing configurations are never overwritten.