- Introduced `useAuthentication` hook to handle session state, PIN verification, and offline mode logic.
- Updated `useRouter` to include type definitions for better navigation instance typing.
- Refined authentication flow with error handling, user session initialization, and token validation.
- Deleted redundant components (`AddActionButton`, `AlertBox`, `AlertStack`, `BackButton`, `CancelButton`, and `CollapsableArea`) and related files.
- Removed unused models (`Book`, `BookSerie`, `BookTables`, `Character`, and `Chapter`) to reduce codebase clutter.
- Updated project structure and references to reflect these removals.
