Function run_agent_loop 

pub async fn run_agent_loop(
    manifest: &AgentManifest,
    query: &str,
    driver: &dyn LlmDriver,
    tools: &ToolRegistry,
    memory: &dyn MemorySubstrate,
    stream_tx: Option<Sender<StreamEvent>>,
) -> Result<AgentLoopResult, AgentError>

Run the agent loop to completion (single-turn, no history).