v0.0.1 of sound_flutter

Sound for Flutter with the goal of no additional system dependencies. Integrates the sound_dart package and uses cargokit to build the native Rust audio library and use it via FFI. Changelog excerpt: - Flutter integration for sound_dart: builds the shared sound_cliRust crate via cargokit and bundles it. Re-exports the sound_dartAPI and adds SoundFlutter.ensureInitialized(). Verified building/bundling/loading on Linux desktop. - SoundFlutter.loadAsset/playAssetto play bundled Flutter assets (with an optional package/bundle).