Function chart_version_for 

pub fn chart_version_for(
    project_version: Option<&str>,
    export: Option<&ExportConfig>,
) -> String

Returns the Helm chart version string.

Resolution order: export.helm.chart_version override -> project_version -> "0.1.0".

use lightshuttle_export::resolve::chart_version_for;

assert_eq!(chart_version_for(Some("1.2.3"), None), "1.2.3");
assert_eq!(chart_version_for(None, None), "0.1.0");