dsh-sales: DeepSeek Harness Sales Execution Plugin

`dsh-sales` is a DeepSeek Harness plugin designed to advance confirmed customer opportunities into a closable, reviewable, and scalable sales operations layer through standardized workflows. It supports material transformation for formats such as Markdown and CSV, pre-validation, and end-to-end management, ensuring that sales artifacts comply with qualification, quoting, and other relevant stages. Rather than directly operating a CRM or contacting customers, it functions as a monetization execution layer that collaborates with other plugins in the ecosystem to convert marketing demand into sustainable business operations.