Function exec_agent_hook 

pub async fn exec_agent_hook(
    hook: &AgentHook,
    hook_name: &str,
    hook_event: &str,
    json_input: &str,
    signal: Receiver<bool>,
    tool_use_context: Arc<ToolUseContext>,
    tool_use_id: Option<String>,
    _messages: &[Message],
    agent_name: Option<&str>,
) -> HookResult

Execute an agent-based hook using a multi-turn LLM query