Galois connections for numeric casts in Rust

A Rust crate implements Galois connections as first-class values for lawful numeric conversions. The library provides composable, property-tested casts between types like f64, f32, u32, and i32. Every connection carries a verified invariant, and the compose! macro builds multi-hop conversions at compile time. The crate is #![forbid(unsafe_code)] and requires Rust 1.88.