Enhance Step Sequencer and API Integration

Commit notes

This commit improves the Step Sequencer by filtering out invalid sample packs and patterns, ensuring only valid data is displayed. It also updates the API client to correctly handle sample pack creation and sample uploads, enhancing data integrity. Additionally, the library page is refined by removing the owned packs tab, streamlining the user interface. These changes contribute to a more robust and user-friendly experience in managing samples and packs.