nx_collide2d.nx

nx_collide2d.nx -- certified composable part: CONTINUOUS (swept) 2D collision with slide response and impulse integration. The gamebench board's own bar for a physics-collision HAVE names exactly three absences (nx_gamebench.nx bit-5 comment): swept/continuous collision, slide-along-surface response, velocity/impulse integration -- this part is those three, gated and mutation-proven. LIB, no main (ecosystem convention, cf. nx_gamesave/nx_swgpu). Integer-only: positions/velocities in plain i64 world units, time-of-impact as a Q8 fraction of one step. Deterministic by construction. Restitution is a Q8 PARAMETER (rule 11: coefficients are data, never buried constants); rest=0 gives pure slide (normal component killed, tangent PRESERVED), rest=C2_Q gives a perfect bounce. license_tier: ORIGINAL expect_exit: 0