- Introduce `BooksSyncContext` for managing book synchronization states (server-only, local-only, to-sync, etc.).
- Remove `UserContext` and related dependencies.
- Refine localization strings (`en.json`) with sync-related updates (e.g., "toSyncFromServer", "toSyncToServer").
- Extend database schema with additional tables and fields for syncing books, chapters, and related entities.
- Add `last_update` fields and update corresponding repository methods to support synchronization logic.
- Enhance IPC handlers with stricter typing, data validation, and sync-aware operations.
- Removed unnecessary React imports.
- Adjusted package.json scripts for Electron integration.
- Updated components to replace Next.js-specific imports with Electron-compatible alternatives.
- Minor tsconfig.json changes for better compatibility.
