- ObjectLayerPairFilterTable blocks all collisions by default in C# binding;
explicitly EnableCollision for all layer pairs (NonMoving/Moving)
- BoxShape takes half-extents, not full size: DynamicBox(scale * 0.5f)
- Floor visual thickness reduced (scale Y 1→0.5), top at y=0 matching collider
- Floor lowered to y=-0.5
- Physics works: cubes and spheres fall and land on floor, no clipping
BroadPhaseLayerInterfaceTable, ObjectLayerPairFilterTable, and
ObjectVsBroadPhaseLayerFilterTable were local variables in the
constructor. After GC collected them, Jolt crashed with dangling
native pointers during PhysicsSystem.Update(). Now stored as readonly
fields with proper Dispose in cleanup. Also fixed Flecs table lock
assertion by collecting RigidBody init list before calling entity.Set().