dsh-product: DeepSeek Harness Product Delivery and PMF Validation Plugin

dsh-product is a core plugin in the DeepSeek Harness ecosystem, focused on product delivery and PMF validation. It does not handle coding or design, but instead leverages the "everything is a plugin" philosophy to turn validated product opportunities into actionable product briefs, gated reviews, and feedback loops. The plugin covers end-to-end management, including strategy definition, POC/MVP validation, and launch assessment, and collaborates with plugins such as dsh-idea and dsh-business to ensure a smooth path from opportunity to implementation and growth handoff.