Spanners are lost with `Save selection` when they are at the end of the selected range

Issue type

Opening/saving issue

Description with steps to reproduce

Spanners that extend to the end of a selected range are lost in the new score created by Save selection.

Supporting files, videos and screenshots

• First half of the video shows spanners being lost when they are at the end of the selected range.
• Second half shows that they are stored correctly when they are at the beginning of the selected range.

https://github.com/user-attachments/assets/02e8b6c7-aa2f-492a-99a5-d644c34369b5

In which versions of MuseScore Studio is this issue present?

Found in latest nightlies

Regression

No.

Operating system

Ubuntu 24.04.4 LTS

Additional context

No response

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible

Reproduce the issue with MuseScore Studio's Save selection workflow, following the attached video and checking spanners at both ends of the selected range. Trace the selection-saving entry point and verify that spanners extending to the range end are retained in the new score, while preserving the existing beginning-of-range behavior.