Show banners on /blog

[melchoyce]

Feature suggestion

When @igorkorenfeld and I originally chatted about it, we decided against putting banners on the blog page since not every post had one. However, we've been chatting with @mitogi and the team working on writing guidelines for the banners and have reconsidered.

Other considerations and design implementation suggestions

Here's a mockup using a 16:9 aspect ratio, where the image is cropped to just the center:

Figma link