- Replace client-side IndexedDB with server-first document storage
- Add document caching layer for offline capability and performance
- Implement document transfer during anonymous-to-authenticated account linking
- Add database indexes for improved query performance
- Update document contexts to use new caching system
- Refactor document upload and deletion APIs
- Add audiobook pruning for missing files
- Improve test isolation with namespace support
- Add unit tests for document cache and transfer functions
