//! RPLidar serial driver stub (feature `lidar`).
//!
//! Requires `serialport` and `rplidar-rs` crates + real hardware.
//! The functions below are stubs matching the §9.2 spec — they compile
//! but panic at runtime with [`todo!`].
/// Open an RPLidar device on the given serial port path.
///
/// **Stub** — needs `serialport` + `rplidar-rs`.
/// Grab a single 360° scan from an open RPLidar device.
///
/// Returns points in polar→Cartesian form `[x, y, 0.0]` (2D scan, z = 0).
///
/// **Stub** — needs `serialport` + `rplidar-rs`.