🎆 Fireworks Burst - 2D Cross-Section: Shell Ballistics, Star Drag and Burst Geometry

2D companion of the fireworks particle simulator: a cross-section of a shell flying with gravity, drag and wind, bursting at the fuse time into stars that follow drag-and-gravity trajectories around a freely falling centre, with live graphs and numerical checks of ballistics, terminal speed, drag stopping distance and burst momentum.