Export to CDXML losts multi-tailed arrows and collapse text labels to many text labels stacked one over another

[AlexeyGirin]

Steps to Reproduce

1. Open Molecules (clean canvas)
2. Load from ket file (unzip first): Export to CDXML losts multi-tailed arrows and collapse text boxes to muli-textboxes stacked one over another.zip

3. Export canvas to CDXML file and load it back as new project

Actual behavior
Multi-tailed arrows are missed, each text label splitted on many per each line and all of them are stacked one above other

Expected behavior
All elements (such as multi-tailed arrows) are in place, text labels remain in place and correct

Environment details:

• Ketcher Version 3.12.0-rc.1 Build at 2026-01-08; 17:35:48
• Indigo Version 1.40.0-rc.1.0-g63d8f2068-wasm32-wasm-clang-19.0.0
• Chrome Version 143.0.7499.170 (Official Build) (64-bit)
• Win10