Sends a prompt to a local Ollama server and returns assistant text.
Supports optional image inputs by converting them to base64 when SupportsVision is enabled.See IChatTask. Ollama API:
https://docs.ollama.com/ParametersreqMessage and optional images.
streamOptional partial callback; final text is still returned.
ctCancellation token for request/HTTP.
ReturnsChatResponse containing text plus raw JSON for inspection.