Incorrect numbering in sequence mode when adding Phosphates

[Zhirnoff]

Description:
In Sequence mode, when a Phosphates is added to the sequence, the numbering does not restart. Instead, the numbering continues from the previous sequence. This behavior is inconsistent and may lead to confusion when constructing macromolecular structures. The numbering should reset for new components like Phosphates to clearly differentiate them from the main sequence.

Steps to Reproduce

1. Open Ketcher in Macro mode and switch to Sequence mode.
2. Create an RNA or DNA sequence.
3. Add a Phosphates to the sequence.
4. Observe the numbering of the added component.

Actual behavior
The numbering continues from the previous sequence, creating a lack of differentiation between the main sequence and the newly added components.

Also, phosphates at the beginning/end of the chain get counted.

Expected behavior
The adding of Phosphates should start new count, indicating that they are separate entities from the existing sequence.

Terminal phosphates should not get counted.

Screenshots
Sequence mode

Snake mode

Counting of terminal phosphates

Desktop:

• OS: Windows 11
• Browser Chrome
• Version 131.0.6778.205 (Official Build) (64-bit)

Ketcher version
[Version 3.1.0-rc.6]
Indigo version
[Version 1.29.0-rc.1]
The bug was created as an addition to #6288 because this functionality wasn't fixed and requires updating a large number of screenshots.

[AlexeyGirin]

Moved to 3.2 rc2 after grooming