Replace the flat-grey torus asteroid belt with a swarm of 60 individual
rocks per belt — one shared jittered-icosphere mesh asset scaled, rotated,
and palette-tinted per instance (5-entry greyscale/brown material set).
- New GeneratedAsteroid data (position/scale/rotation/material_index)
generated deterministically alongside the belt, preserving the
same-seed-same-galaxy invariant
- New build_asteroid_mesh + asteroid_material_palette helpers
- ContentAssets drops belt_material, adds asteroid_mesh + asteroid_materials
- spawn_system_contents signature simplified (no more &mut Assets<Mesh>)
- Belt entity is now a no-mesh parent (Mineable/Identifiable/...) with
rock meshes as children — sets the stage for per-asteroid mining
- Bundles the POI component/marker scaffolding (poi.rs) and per-system
contents generator (contents.rs: planets, stations, anomalies, stargates,
gas clouds) that the asteroid rendering sits on top of
- Tests: asteroid_generation_is_deterministic,
asteroid_positions_stay_inside_annulus
francy51
4240c2b2ef