Show HN: Artemis II Moon Mission Simulator in the Browser

I built a browser-based simulator of NASA's Artemis II mission — the first crewed lunar flight since Apollo 17. You fly the actual mission profile: launch to parking orbit, raise to High Earth Orbit, fire Trans-Lunar Injection when the Moon is in position, swing behind the Moon, and return to Earth. The physics uses RK4 integration with real Earth and Moon gravity. Have fun experimenting with what happens if you don't time it right!