backslash (\) wrongly add before each dollar sign ($) in the preview mode

### ⚠️ This issue respects the following points: ⚠️

- [x] This is a **bug**. Not a [question or feature request](https://github.com/gsantner/markor/issues/new/choose).
- [x] The topic is **not** already reported at [Issues](https://github.com/gsantner/markor/issues?q=#js-issues-search). _(I've searched it and checked most recent issues)_.
- [x] Markor **is** up to date. See [Releases](https://github.com/gsantner/markor/tags) for the latest version. Updates are available from [F-Droid](https://f-droid.org/en/packages/net.gsantner.markor/) and GitHub.
- [x] The bug is still present in the latest development version (git master). (Please [download](https://nightly.link/gsantner/markor/workflows/build-android-project/master) and try the test version of Markor, named **Marder**. Don't worry; Markor and Marder appear as completely separate applications. You can install both side-by-side, and Markor settings are not touched. In case the issue is resolved there, you don't need to create a bug report. The change will be part of the next Markor update.)

### Description

Inside the code block. Whereever there is a dollar sign, a leading backslash will be wrongly add to it in ` Preview Mode`.

# Edit Mode

# Preview Mode

### Steps to reproduce

1.
2.
3.

### Information

Android version: 15
Device (phone model): Samsung Tab A9
App Version: 2.16.1 (lastest in FDroid)

### Source

F-Droid

### Format / File type

Markdown

### Additional info / Log

```shell
-
```

Reproduce the issue in Markor's Markdown Preview using a fenced code block containing dollar signs, comparing it with Edit Mode. Trace the Markdown preview/rendering entry point and verify that preview output no longer adds a leading backslash before dollar signs while preserving the code block content.

Written by the indexing model from the issue text.