Remove the llm-image-offload package and every registration it needed. The
recovery branch lives in dsh-llm-retry, which already sits on the
agent/request-error waterfall: an IMAGE_OFFLOAD_REQUIRED failure advances the
image/offload watermark by the count the adapter names and retries the step
outside the provider retry budget. Drop pre-dispatch planning with it: routes
no longer declare a request-image budget on their model info, and the byte
checks that stay in the DeepSeek and pi-ai adapters are provisional until the
provider reports uncacheable images itself.