- Implement `Content` model for converting Tiptap raw data into HTML and plain text.
- Add `Model` for storing and managing AI model configurations with pricing and metadata.
- Introduce `Story` model to handle verbal styles and linguistic properties for diverse narrative structures.
- Update `book.repository.ts` to refine `updateBookBasicInformation` and `insertNewPlotPoint` methods, removing unused parameters and optimizing queries.
- Implement `CharacterRepo`, `LocationRepo`, and `UserRepo` for managing character, location, and user data with SQLite.
- Add methods for performing CRUD operations on characters, locations, and users, including attributes and metadata handling.
- Integrate error handling with multilingual support (`fr` and `en`).
- Support data encryption and synchronization using the existing database utilities.
