Function create_model 

pub async fn create_model(
    model_spec: &str,
    backend_config: BackendConfig,
) -> Result<Box<dyn Model>>

Factory functions for creating unified models Create a model from a model specification

Examples:

• “ollama/qwen3-coder:30b” - Explicit backend
• “qwen3-coder:30b” - Auto-detect backend
• “gpt-4” - Search backends