pub fn call_anthropic(system: &str, user_prompt: &str) -> Result<String, String>Expand description
Call the Anthropic Messages API with separate system and user prompts.
Reads ANTHROPIC_API_KEY from environment. Model defaults to claude-sonnet-4-5
but can be overridden via FERRO_AI_MODEL.
Uses Anthropic best practices: system prompt with cache_control, assistant prefill, temperature 0.2 for deterministic output, and 60-second HTTP timeout.