How can society put costs on public servant treachery?

Right now you can't, because voting has proven ineffective for that particular problem, and adding anything that would do so would be blocked by the very people that you are trying to police since they are the rule makers.

But if we had to make it all over again?

Make mandate shorts. Make lobbying illegal. Make trying to game the system be paid by extremely harsh prison sentences. Create an institution that is in charge of corruption of the government that is independent of the government.

There is a lot to do.

By voting them out.

Some sort of penalty for passing unconstitutional laws sounds good but not sure how it could be implemented in practice. They did swear an oath to uphold the constitution.

exactly, that's simple incentives. When the game is set this way, you just keep playing until you win.