Fix: frontpage news codeblock linebreaks & add news fixtures

[m1rm]

Tip

This pull request aims at fixing missing line breaks in frontpage news code blocks. Additionally, for local development, news fixtures for the frontpage news section were added.

Issue linebreak loss

vendor code details

The `truncatewords_html` filter uses the TruncateWordsHTMLParser -> The filter is in: `.venv/lib/python3.14/site-packages/django/template/defaultfilters.py` -> The Truncator is in: `.venv/lib/python3.14/site-packages/django/utils/text.py`

class TruncateWordsHTMLParser(TruncateHTMLParser):
    def process(self, data):
        data = re.split(r"(?<=\S)\s+(?=\S)", data)
        output = escape(" ".join(data[: self.remaining]))
        return data, output

-> I think there the \n is lost because of the \S and \s usage (see https://docs.python.org/3/library/re.html)

Potential fixes

Using the linebreak filter
Commit: f543590 -> might not be a good choice, see comment screenshot

Using a custom filter
The custom filter is based on the builtin filter and only changes the behavior for <pre> blocks
Commit: d05be81

News fixtures

In order to debug this issue locally, fixtures for news are added (they are fully made up, I am not emotionally attached to the content so feel free to change it).

Tests

I added a test for newline preservation. Not sure if we need it but we can always remove it.

Fixes #573

[m1rm]

converted to draft again bc. I am checking if the "linebreak" filter might add too many linebreaks. @jelly @christian-heusel because it is applied to all the content (not only codeblocks)

[m1rm]

Appearance when using the linebreak filter:

Appearance when using the custom filter: