Function resolve_param_references 

pub fn resolve_param_references(
    yaml: &str,
    param_values: &ParamValues,
) -> String

Resolve parameter references in a YAML string.

Replaces "$identifier" and "$identifier.path" with their values. Works on the raw YAML string before parsing, matching the JS approach of JSON.stringify → regex replace → JSON.parse.

If a reference is not found in param_values, it is left unchanged (the filter/transform will see the raw $... string).