Change LP Staking (seigniorage mining) Minimum to a CoolDown Period

Currently, LP stakers for USDC/USDx have a 24 hour minimum staking period.

We propose to change this to a 24 hour cooldown period, where during the cooldown, LP's get no seigniorage rewards. This incentivizes longer lockups and potentially better price stability.

The proposed change will maintain the current staking minimum time variable but just change its value to 0. It will also introduce a secondary cooldown variable that checks the time a user is committed to withdrawing his/her LP.