memos Link preview

Is your feature request related to a problem?

Many social apps have link preview feature, e.g. twitter, mastodon. After entering a link in a tweet, Twitter will automatically grab a preview for the link and render it as a card.

Since memos essentially aims to provide a twitter-like posting experience, I think it'd be nice to have this feature considering the urls nowadays tend to be long and ugly and markdown []() does not entail picture previews, and it is convenient.

许多应用都有链接预览功能，例如Twitter、Mastodon。在推文中输入链接后，Twitter会自动抓取链接的预览，并将其呈现为卡片形式。

由于Memos本质上是模拟类似twitter的发布体验，考虑到现在的urls往往又长又丑，而且markdown的[]()很不显眼，所以有这个feature还是很有必要的。

Describe the solution you'd like

Try rendering the first URL in the post as a preview card. It could be problematic when you have several links and I havent thought about it yet. Maybe just rendering the first one is okay.