dsh-rental-insurance: Rental Insurance Recommendations Plugin

The DSH (DeepSeek Harness) plugin, `dsh-rental-insurance`, follows the “everything is a plugin” design philosophy and aims to address agents’ imprecise reasoning when handling task-specific business logic such as rental insurance. Implemented in pure Node.js, it provides local support for insurance decision-making without requiring an internet connection. Users can install it via a specified command and directly invoke its registered tools within a session to obtain clear insurance recommendations, serving as a local logic layer for the agent.