C3 (Pi openai-completions relocation): tool messages are text-only on
the OpenAI chat wire — image parts inside role:tool content 400 on
strict validators. Images from a consecutive tool-result run now batch
into ONE synthetic user message appended after the run (a user message
may not interrupt tool responses answering the same assistant's
tool_calls); an image-only result carries a '(see attached image)'
pointer placeholder. Applied at the typed conversion layer, so every
chat dialect gets the universally-valid shape.
Verified: models+sampling-types+sampler+chat-state+shell all green,
clippy clean.
ZacharyZhang-NY
2524c33a5b