dsh-ui-settings-icons: DeepSeek Harness Settings Sidebar Custom Icon Plugin

`dsh-ui-settings-icons` is a DeepSeek Harness (DSH) plugin designed to address the visual monotony caused by missing icons in the Settings sidebar. It introduces a `settings.section.icon` slot mechanism, allowing developers to inject custom SVG or React icons by matching section IDs. The plugin includes built-in 16x16 vector preset icons for common capability packages and supports keyboard navigation, wide/narrow sidebar toggling, and more. To install it, ensure the DSH version is 0.1.5-rc.1 and stop the web process.