// Slice 1 has no collision systems yet — geometry primitives in `geometry.rs` are
// defined and unit-tested but not yet wired into any Bevy systems.
//
// Future systems to add here:
//   - `projectile_hits`: query projectiles against damageable entities using `overlaps`
//     or `segment_vs_sphere` (for fast-moving projectiles that might tunnel).
//   - `ship_separation`: push ships apart when they get too close using `separate`.
//   - `proximity_triggers`: emit events when entities enter/exit a radius.
//
// When adding these, register them in `PhysicsPlugin::build()`. They should run on
// `FixedUpdate` for determinism (see ARCH-9 in the docs).
