Add open graph image to SEO config

[aaroncox]

Image is currently missing. It should be something that represents the network the page is on. According to a quick search this image should be 1200 x 630 (1.9:1).

The code can be added here as return property named open_graph_image:

https://github.com/greymass/2nicove/blob/df9a5f60677de093f363842c79c4bbdcb0ba73ff/src/routes/%2Blayout.ts#L5-L13