Similar to the OP, how would you stop this?

- You get 200 years to prepare, with the resources of all human civilization on Earth and anything from the solar system you can find in that time
- you're limited to known physics, no breakthroughs
- you know its abilities: weight 10 metric tons, maximum acceleration/deceleration between 25g and 75g, maximum velocity 0.25c, hull is a single piece bonded by strong nuclear force, no weapons
- you can't cheat with deterrence strategies, you have to actually defeat/incapacitate it
- it knows where you are