feat: avian f64, which means orbit springs work now

fix: parts have initial velocity matching parent planet, and orbit indicator uses relative velocity

fix: world config is on client too now

chore: please the clippy

feat: avian!

Merge branch 'core/rewrite-it-all-again-lmao' into 'master'

unified

See merge request starkingdoms.tk/starkingdoms.tk!5

Chassis -> housing

chore: code cleanup

chore(part): part fix #1

fix: parts

chore: newtype linearsplines for particle system

feat: mod spawning