Function spawn_claude_code_cli 

pub async fn spawn_claude_code_cli(
    registry: Arc<ProcessRegistry>,
    event_sender: Sender<AgentEvent>,
    cancel_token: CancellationToken,
    config: ClaudeCodeCliConfig,
) -> Result<i64, String>

Spawn Claude Code CLI and stream its output as AgentEvents.

Returns the registered run_id from the ProcessRegistry.