B9109: preemptive fix for mtp & mmproj fix soon? It appears so

Summary: spec: process images through the draft context - this directly addresses the mmproj + MTP crash. Previously images (mmproj) couldn't be processed through the speculative/draft context at all. This commit adds that capability. That's the actual fix in progress. server: fix mtmd draft processing - mtmd is the multimodal (mmproj) handler. Explicitly fixing draft processing for multimodal means they know about the crash and are targeting it.