This commit adds a native calculation engine by integrating the pre-compiled SoulverCore Swift library. A Swift package (`SoulverWrapper`) was created to act as a C-compatible FFI bridge, allowing the Rust backend to call into the library (because the library does not include de-mangled names). The build process was updated to compile this Swift wrapper and correctly bundle the necessary shared libraries and resources for both development and production environments. A new Tauri command, `calculate_soulver`, exposes this functionality to the Svelte frontend.
In the future, we will be using this functionality to improve the built-in calculator.
