dsh-cool-theme: DeepSeek Harness Theme Plugin

`dsh-cool-theme` is a theme plugin for DeepSeek Harness, following the “everything is a plugin” philosophy. Maintained by CoolTea, it supports Dark/Light/System switching. It includes 34 built-in preset themes (such as Catppuccin and Dracula) and provides customization, sharing, and import features. The installation command is `dsh plugin add dsh-cool-theme`, requires Node.js >=22.19, and is released under the MIT License.