dsh-habit-build: DeepSeek Harness Habit-Building Plugin

The `dsh-habit-build` plugin for DeepSeek Harness (DSH) is designed specifically for habit-building scenarios. It is maintained by `uckkk`, built with a pure Node.js tech stack, and has no network dependencies. Users can install it with `dsh plugin add github:uckkk/dsh-habit-build`; after installation, invoking the `habit_build` tool in a session provides parent-child education plans. This plugin is suitable for offline environments and runs with the permissions of the current process.