Function run_agent_loop_with_nudge 

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

PMAT-177: Agent loop with tool-use nudge. If first turn has no tool calls, retries once.