More work on the blog to Bluesky API integration.

As I understand it, a 'link card' will take priority over an image so you can't have both, but you can include an image with that card.

This is, therefore a test to see if marking an image as featured (I give it the class 'feat') will have it be correctly identified, uploaded and attached to the link card for this post.

If a post is less than 275 characters I should also not be generating a link card but just sending the full text of the post adding an image if applicable.