DeepSeek Harness Background Image Plugin (dsh-bg-changer)

The `dsh-bg-changer` plugin enables DeepSeek Harness (DSH) users to customize the UI background. By adding configuration entries in the settings, it supports uploading local images and adjusting layout, opacity, blur, and the UI’s own transparency. The plugin has zero dependencies and requires no build, stores data locally, supports multiple image formats and preview adjustments, and aims to provide a low-intrusive skinning solution. Installation and uninstallation are handled via scripts, and it has been verified in the DSH v0.1.6-alpha.1 environment.