[BUG] Indented code blocks not highlighted in edit panel

[polter-rnd]

Indented code blocks (e.g., within bullet lists) are not receiving syntax highlighting in the edit panel, though they display correctly in the preview panel.

Expected behaviour

Indented code blocks should be highlighted in the edit panel, just like in the preview panel, ensuring consistency.

Actual behaviour

Steps to reproduce

Example markdown file:

Without indentation all fine:

```bash
$ echo Hello world
```

But without indentation it's not highlighted in edit panel.

- See:

  ```bash
  $ echo Hello world 2
  ```

[pbek]

You need to intend with at least 4 spaces.

See: https://www.qownnotes.org/getting-started/markdown.html#_4-spaces-fence