Export to CML doesn't work for s-groups of Nucleotide Component type and atom with attachment points

**Steps to Reproduce**
1. Go to Molecules mode (empty canvas)
2. Load from KET: [Export to CML doesn't work.zip](https://github.com/user-attachments/files/21632943/Export.to.CML.doesn.t.work.zip)

3. Save canvas to CML and load result to clear canvas

**Actual behavior**
Canvas is incorrect

**Expected behavior**
Export/import works correct

**Environment details:**
- Ketcher Version 3.7.0-rc.1 Build at 2025-08-04; 22:44:37
- Indigo Version 1.35.0-rc.1.0-g1900fe55e-wasm32-wasm-clang-19.0.0
- Chrome Version 138.0.7204.97 (Official Build) (64-bit)
- Win10

Found while testing: https://github.com/epam/ketcher/issues/6150