DeepSeek Harness Web Background Settings Plugin

The `web-background` plugin for DeepSeek Harness is designed to address web interface background control needs, supporting solid colors, images, and opacity adjustments. Settings are stored in the browser's local storage, supporting multi-tab synchronization and one-click reset. The plugin allows adjusting the visual appearance of the interface without modifying code, making it suitable for debugging and demonstrations. To install, ensure that the Harness is already installed and that you have Web profile permissions. It supports installation from a Git repository or a local directory, and requires a web service restart to take effect.