Give house foundations negative melee armour (like rams)

It nerfs house walling to some extent without upsetting the eco balance.

It doesn't stop players from pre walling, but it does really hurt players who double wall while busy being attacked. So you can still slow down an invasion but certainly not to the extent we currently have.

Negative melee armour only so the archer dominance in feudal isn't exacerbated.

You can still wall with other buildings but they aren't dirt cheap like houses