dsh-workbuddy-ppt: DSH Editable PPTX Generation and PPTD Validation

`dsh-workbuddy-ppt` is a plugin for DeepSeek Harness (DSH) designed to generate editable PPTX documents locally. It provides built-in Kimi-compatible authoring skills and a deterministic PPTD v2 validation mechanism, supporting both PPT and Slides modes. It includes the `dsh-pptd` CLI tool with features such as conversion, inspection, rendering, and screenshot generation, without relying on external runtimes. The plugin is MIT licensed and suitable for technical teams that need to generate high-quality, structured PPTX documents in DSH environments.