wallpaper-engine-dsh: Using the Wallpaper Engine Library as a DSH Interface Background

`wallpaper-engine-dsh` is a plugin designed for DeepSeek Harness (DSH) that renders local Wallpaper Engine wallpapers (videos and web pages) as Web interface backgrounds. It supports wallpaper library scanning and search, smart masking (automatically adapting to theme brightness), manual cropping and layout adjustment, real-time adjustment of blur and glass effects, and carousel lists. It also features FPS monitoring and fault-tolerant playback. Installation is simple, although .pkg wallpapers are not supported on the desktop side. Overall, it provides developers with an attractive and stable solution for personalized backgrounds.