Link preview should show board, and not generic hypercerts image

[Jipperism]

Link preview should show board, and not generic hypercerts image

@bitbeckers @holkexyz this needs extra thought

[holkexyz]

@Jipperism in the meantime we could set a specific generic hyperboard image, instead of the generic hypercert image, right?

[Jipperism]

@holkexyz yes that would be straightforward