- Created state normalization utility (stateNormalization.ts) with functions:
* normalize/denormalize for converting arrays to normalized state
* addToNormalized, updateInNormalized, removeFromNormalized
* Helper functions for working with normalized state
- Applied normalization to LibraryStore (items and favorites)
- Updated storeSelectors to convert normalized state to arrays
- Updated DashboardPage components to use new selectors
- Updated tests to work with normalized state structure
- Improved performance with O(1) lookups instead of O(n) array searches
