Lexical version: indirect dependency (version not exposed by Sveltia CMS)

Steps To Reproduce

1. Create or edit a markdown document in the Sveltia CMS editor.
2. Switch to markdown view.
3. Add nested fenced code blocks using 4 backticks to wrap content that contains a 3-backtick code block, e.g.:

````markdown
## Development Setup

After cloning, run:

```bash
pip install pre-commit
pre-commit install
```
````

4. Save the markdown content.
5. Close the editor.
6. Reopen the same markdown document in the editor.
7. Observe the malformed markdown output.

Link to code example: https://playground.lexical.dev/#doc=H4sIAAAAAAAACtWVwW7CMAyGX6Uy14DKhtYtt0l7gEnsNk1qaEwbkTpV6rAh1HefUjYGnBCMiZ0S_7F_f744a0Bt2PkpK0aQa_DOcTyLyljtkUC-HgQaWRkLMhUwd75W3F9rpxEkUFQsCGh5ZaMAAhg_GCTkeR6DVRPlwmkcVqasrCkrBgFL9K1xBHIsYKu_bJKbQAUHxfG9E2cQ1MovtHunEzn6ZKuoDKrEnuTLxRrCmUe12DM4B3UwSJ5widY1NRInU-TQnEM9s65YHId8sZke54w-KawjQ6VIfCD530fK83ym2uqPxjiVsjFNYqhlZW3SeBwWrq4NXzv0FvSb_cqBf2-_XRLxOMbuTYA2HoueSVKw9qdVNDSkkTZtd9wO5tyuSgnbzXuCc_8l7dF10bvlqVqiBjnOsjSdZHc3k_txJqB1wRex7tmqVeldIL1bDeno9mGUQvcJoRgyfvsGAAA

Click the Convert from Markdown button

The current behavior

When reopening a document that contains nested fenced code blocks (4 backticks wrapping a 3-backtick fenced block), the editor corrupts the structure: it misinterprets and breaks the nesting boundaries, leading to malformed markdown where code blocks are opened/closed incorrectly.

The expected behavior

The nested fenced code block structure should be preserved exactly as it was entered, with the outer 4-backtick fence correctly containing the inner 3-backtick code block, following CommonMark rules for nested fences.

Impact of fix

Severity: High for users documenting examples of code within markdown (e.g., docs, tutorials).

Frequency: Happens whenever nested code fences are used and the document is reopened.

Who would benefit: Content authors using advanced markdown features; anyone relying on accurate editing of code examples.

Metrics (if known): Affects all markdown fields in the CMS editor where nested code blocks are used.