dsh-session-icons: DSH Session Title Icons Plugin

`dsh-session-icons` is a helper plugin for DeepSeek Harness (DSH) designed to reduce clutter in session list titles. The plugin leverages AI to automatically generate 24x24 monochrome SVG icons for each session and inject them into the sidebar to support visual identification. Core features include icon generation and injection, a disk-based caching mechanism (with support for sharing under the same name), and output safety constraints. The plugin depends on the `dsh web` environment, works with default configuration, and supports adjusting the cache count and timeout via the configuration file.