dsh-autovision: Adding Visual Capabilities to DSH Text Models

The `dsh-autovision` plugin provides native visual capabilities for DeepSeek Harness (DSH) text-only models. By registering a transparent twin provider, it automatically routes image requests to a configured multimodal model for transcription and then injects the resulting text into the context, enabling “paste-to-text.” Users do not need to switch models or expose API keys, and can paste images directly or read files through Agent tools. The plugin is easy to install and offers persistent configuration and an LRU cache to mitigate latency, but users should be aware of limitations such as the first image being skipped, a 5 MB file size limit, and minor UI display issues.