Style tags get removed when exporting flashcards in .txt format

I noticed that when exporting notes on .txt format, all `` tags (not inline styling) for adding custom CSS to flashcards get removed.
I need to export flashcards as plain text for translating them, but this breaks the cards that were using custom styling and I can't find a workaround.

Version ⁨25.02.4 (a5c33ad0)⁩
Python 3.9.18 Qt 6.6.2 PyQt 6.6.1

Start by reproducing the issue through the flashcard .txt export path described in the report, comparing cards with custom tags against cards using inline styling. Trace where the exported text is assembled and verify that non-inline style tags remain available for translation; add or update regression coverage for both cases.

Written by the indexing model from the issue text.