dsh-generative-ideas: DeepSeek Harness Roadmap Ideation Plugin

`dsh-generative-ideas` is a roadmap ideation plugin for DeepSeek Harness. It uses a background headless agent to analyze competitors and constraints, generating four distinct strategic options. Users can compare these options in a panel, with support for operations such as Reroll and Push, and finally export the selected roadmap as a `goal.md` file. Through structured deep research and comparison, the plugin helps developers quickly identify the right goal.