//! Native entry for the engine-native UI spike.
//!
//! Opens a real OS window (winit, via eframe) whose wgpu device drives the
//! shared `brep-render` engine. Needs a display + GPU to actually run; on a
//! headless box this still `cargo build`s (the CI/gate signal), and the web
//! target (`lib.rs` + `WebRunner`) is the interactive verification path.