Refactor backend and frontend for sample pack slug migration and route enhancements

Commit notes

- Removed unused dependencies from go.mod to streamline the backend. - Implemented a migration function for adding and populating the slug field in the sample packs table. - Updated frontend routes to include new paths for sequencer and market pack details. - Added type definitions for new routes in the React Router setup, enhancing type safety and clarity. - Improved the PackDetailPage and MarketPage components with better state management and UI consistency.