Fallback to the Future: Atom Feed Support

This release introduces seamless compatibility with Atom feeds and other sources that rely on the updated attribute. [#39]

The card now gracefully falls back to the updated field whenever a published date is missing. This ensures your feeds—such as GitHub releases—always display the correct timestamps instead of unsightly "Invalid Date" errors. I've applied this logic to both individual feed entries and top-level channel information to keep your entire timeline perfectly accurate.