AxoLabs: incorrect auto‑pairing / hydrogen bonds for complementary sequences

**Source task:**
https://github.com/epam/Indigo/issues/3250

**Preconditions:**

Macromolecules mode enabled.
Paste from clipboard, format = AxoLabs.

**Steps to reproduce (case 1):**

1. Open Paste from clipboard.
2. Paste:
```
5'-AAAp-3'
5'-UUUp-3'
```
3. Add to canvas.

**Actual behavior**

**Expected behavior**

**Steps to reproduce (case 2):**

1. Open Paste from clipboard.
2. Paste:
```
5'-GCUA-3'
5'-CGAU-3'
```
3. Add to canvas.

**Actual behavior**

**Expected behavior**

**Environment details:**
- OS: MacOs Tahoe version 26.2
- Browser Chrome Version 143.0.7499.170
- Version Ketcher 3.12.0-rc.1
- Version Indigo 1.40.0-rc.1.0-g63d8f2068-wasm32-wasm-clang-19.0.0

Reproduce both cases through Paste from clipboard in Macromolecules mode using the AxoLabs inputs shown. Trace the AxoLabs parsing and complementary-sequence auto-pairing path; done means both examples produce the expected pairing and hydrogen-bond structures in Ketcher.

Written by the indexing model from the issue text.