The download modal's step shared the 'locationStep' id with the import
modal, so getElementById('locationStep') could resolve to the wrong
element depending on template include order. The import flow relied on
an injected display:block !important rule to work around it.
Rename the download modal's step id and update all references so each
modal owns a unique step id.
Auto-select the first (newest) version for URLs without an explicit
modelVersionId, matching the existing batch flow, so users can proceed
to location/download without manually picking a version.