Audio Spleeter and Remix

1. Significantly improved the speed of two-stem and five-stem audio separation. 2. Added Metal GPU acceleration and optimized spectrum analysis and audio reconstruction. 3. Significantly reduced peak memory usage during five-stem extraction. 4. Optimized parallel processing for different devices, allowing five-stem extraction to run on more older devices. 5. Improved progress reporting for inference, merging, and encoding. 6. Optimized automatic gain and output peak protection to reduce clipping in separated audio. 7. Fixed playhead positioning, tap-to-seek, and replay issues in Remix. 8. Fixed Remix ending early when mixing tracks of different lengths. 9. Improved the Recent Extractions list and multi-selection interface. 10. Fixed button labels, point prompts, and display issues in the download edition. 11. Fixed several extraction failure, file import, and stability issues. 12. Reduced the app package size.