dsh-theme-aurum: DSH Gilded Theme Plugin

The `dsh-theme-aurum` plugin for DeepSeek Harness (DSH) transforms the web interface into a “gilded luxury” style by overriding native components. It uses the OKLCH color space to implement rounded sidebar cards, gold-gradient chat bubbles, pill-shaped tool-card states, and a gold shimmer effect on the input dock. The plugin supports light/dark mode switching, responsive layouts (covering resolutions from 360 to 1920), and coexistence with multiple plugins, and is compatible with DSH Web version >= 0.1.0-rc.6. Installation requires terminal commands, and code changes require reinstallation or restart.