Function select_infrastructure 

pub async fn select_infrastructure(
    provider: &CloudProvider,
    step_number: u8,
    client: Option<&PlatformApiClient>,
    project_id: Option<&str>,
) -> InfrastructureSelectionResult

Select region and machine type for Cloud Runner deployment

Uses dynamic fetching for Hetzner to get real-time availability and pricing. Falls back to static data for other providers or if API fails.