Function load_lfm2_model 

pub fn load_lfm2_model(
    model_path: &str,
    ctx: Arc<WgpuContext>,
    engine: Arc<ComputeEngine>,
    lora_config: Option<LoRaConfig>,
) -> Result<Lfm2Model, String>

Load the model in model_path (config.json plus safetensors).