dsh-image-container: Image Gallery and Lightbox Plugin for DeepSeek Harness

dsh-image-container is a DeepSeek Harness (DSH) plugin designed to replace the default image display with gallery and lightbox functionality. It supports grid layouts and full-screen interaction, and requires the `conversation.message.images` slot. When installing it, make sure the environment variables include `dsh`, and restart the Host after installation. This plugin is specifically intended for DSH 0.2.0-rc.2 and can be installed using the `dsh plugin add` command.