Hairpins not starting or ending on notes get lost in MEI

Issue type

Import/export issue

Description with steps to reproduce

1. Add hairpins
2. move start or end to a tick away from the note
3. export to MEI
4. load the exported file

Supporting files, videos and screenshots

What is the latest version of MuseScore Studio where this issue is present?

4.5.2

Regression

No.

Operating system

macOS 15

Additional context

• Spanners starting on notes but not ending on notes get exported, but miss their end points.
• Same behavior for all text lines

Expected behavior would be to export spanners with @tstamp and @tstamp2 attributes rather than @startid and @endid.

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 by creating hairpins or text lines whose endpoints fall a tick away from notes, then export and reload the MEI file. Inspect the MEI export path for spanners and compare how endpoint-based and timestamp-based positions are written; done means both start and end positions survive the export and reload.