Make the base_time > 0 hard req obligatory for "Build Base"
All the extra building actions except Build Base and Build Road (which is about to change in #42510) have terrain xxx_time > 0 as an obligatory hard requirement. Make Build Base consistent with the others.
All the extra building actions except Build Base and Build Road (which is about to change in #42510) have terrain xxx_time > 0 as an obligatory hard requirement. Make Build Base consistent with the others.