Anthropic Messages API on a SpicyAPI text model

Accepts an Anthropic Messages request (model, system, messages with text / image / tool_use / tool_result blocks, max_tokens, temperature, top_p, top_k, stop_sequences, tools, tool_choice, stream) and translates it to a chat completion internally. stop_sequences becomes the model's stop field, and tool_choice.disable_parallel_tool_use: true becomes parallel_tool_calls: false; a model that does not declare the target field rejects the request with 400 instead of ignoring it. Non-streaming calls return an Anthropic message object. Streaming calls emit message_start, content_block_start, content_block_delta, content_block_stop, message_delta and message_stop events. Errors use the Anthropic {type:"error",error:{type,message}} shape.