[Improvement] SYST-703: Improves the RichEditor markdown to html result.

[alimnfl]

Description:
This pull request improves the consistency and reliability of the markdown-to-html conversion process. Previously, some markdown content was not rendered correctly due to incomplete filtering and structural inconsistencies.

Changes:

1. Adjust list spacing for more consistent rendering.
2. Fix legal document rendering without preprocessingMarkdown by relying on marked with the markdown-live rules.
3. Update the styling of pre elements in Storybook stories.
4. Add a safeguard to ensure content is always wrapped in a paragraph container when necessary.
5. Standardize paragraph and heading generation so that HTML and Markdown structures remain aligned one-to-one.
6. Ensure the Rich Editor correctly handles paragraphs, headings, ordered lists, and unordered lists across all conversion flows.

Source:
[Improvement] SYST-703: Improves the RichEditor markdown to html result.

Tick what you have done:
[x] I have double checked the functionality with the ticket in linear, or any other relevant discussion avenue
[x] I have created/updated any relevant test code
[x] I have tested it myself

[linear]

SYST-703

[github-actions]

Coneto Storybook preview deployed to: https://dev.files.systatum.com/coneto/5cfe2c0e

[github-actions]

Coneto Storybook preview deployed to: https://dev.files.systatum.com/coneto/5cfe2c0e