New Discover Tab with Playlists, Sparks, scrolling animations, and orange theme. Sparks navigation to AI Song Generation. Singing Tool, Stem Generation, and Melody to Song features. Feature flag implementation for new features and tools. New tool selection bottom sheet with category accordion flow and 2x2 tool selection layout. Rotating cover art in the compact mini-player during playback. New Share Playlist sheet with color editor and customization options. New bottom-sheet navigation for Custom Panels and Model Selector sheet. Playback, navigation, AI tools, and existing flows regression testing.