Polyhedron primitives for the RustUse geometry workspace.
`use-polyhedron` is the general 3D polyhedron crate. It starts with vertex, edge, and face records
plus count helpers.
```rust
use use_polyhedron::Polyhedron;
let polyhedron = Polyhedron::from_counts(8, 12, 6).expect("valid counts");
assert_eq!(polyhedron.euler_characteristic(), 2);
```