v1.0.0 of xue_hua_audio

Cross-platform Flutter FFI audio plugin — multi-track playback, progress streams, and microphone recording via Rust/rodio. Changelog excerpt: Initial stable release. ### Added - Multi-track playback— independent XueHuaAudioTrackinstances mixed through a shared rodio MixerDeviceSink. - Audio sources— load from local file path, Flutter Asset (via temp file), or network URL (download with timeout/retry). - Playback control— pause, resume, seek, volume, per-track stop, and engine-wide stopAll(). - Playback progress Stream— track.progressStreampushes XueHuaPlaybackProgressapproximately every 100 ms; sync `playba[...]