dsh-plugin-multimodal: Adding image support to text-only DSH sessions

dsh-plugin-multimodal is a visual sidecar plugin for DeepSeek Harness (DSH), designed to address the issue where text-only main models cannot process image inputs. This plugin receives image attachments via the GUI, invokes a vision-capable sidecar model to convert image content into text descriptions, and then sends the text to the main model, thereby bypassing the "current model does not support images" limitation. Core features include support for pasting images in the Web UI, a see_image tool for processing disk screenshots, and configuration of the vision model via environment variables or configuration files. Users need to install the plugin and restart the DSH Web process to ensure the sidecar points to a real multimodal model (such as GLM-4.5V) and avoids using a text-only model as the vision endpoint. This plugin is suitable for those who wish to...