Feature Request: Export RSS content as local files (PDF, Markdown, HTML, etc.)

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• I've already searched in existing issues and haven't found a similar feature request.

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Is your feature request related to a problem? Please describe.

I would like to request a feature that allows the reader to export previews to save RSS content. Sometimes authors delete their past articles, but RSS readers still keep them in the archive. I hope to be able to export these articles as PDF, Markdown, TXT, HTML, or MHTML files.
​This is similar to a previous issue from two years ago: https://github.com/ReadYouApp/ReadYou/issues/683

Describe the solution you'd like

The app only needs to support exporting the information already received/cached by the RSS feed.

Related links

Perhaps, to make sharing easier, features like "Share as Image" could be added. I have seen many implementation schemes for such Markdown-to-image conversions. You can search for keywords like "Xiaohongshu" (Little Red Book style) on GitHub for inspiration.

Start by reviewing the related issue #683 and tracing how the app receives and caches RSS previews. Define the supported export formats and how cached article information should be represented in each one. Done means users can export cached RSS content as the agreed local file formats.