Eternal Peace trait

Essentially, the opposite of the Eternal War trait of the Cravers.

When Pacifists are on the Senate, the player cannot choose "Declare War" options.

Further potential limiters may be the inability to degrade relationship status (can't choose Cold War from Peace, maybe can't even leave an Alliance), and maybe can't use Black Ops/Mercenary fleets?

Obviously such a race, custom or not, would need to have some form of balance, like lesser cost/more effective diplomacy or better defense on own territory, so they can't be too easily bullied by others.