dsh-image-vision-bridge: Converts images to text descriptions for the DSH main model

# Introduction In agent development with DeepSeek Harness (DSH), a common frustration arises: the primary model is a pure text model, yet users upload screenshots to the conversation. DSH 0.1.1+ implements a built-in fallback for this scenario—requests do not error out, but the model can only see an image placeholder and cannot access the actual image content. To enable the model to truly respond based on images, one must either switch to a multimodal main model or implement a custom forwarding logic layer. dsh-image-vision-bridge solves this problem: it automatically forwards images from user messages to a vision model (defaulting to mimo-v2.5 on the opencode-go route), feeds the returned text description to the main text model, and preserves the original image display in the chat history. DSH's philosophy is "Everything...