- Update return types for IPC handlers in `character.ipc.ts`, `chapter.ipc.ts`, and `location.ipc.ts` for stricter type safety.
- Introduce new type definitions for better structure and clarity.
- Remove redundant console logs and unnecessary comments for cleaner code.
- Introduce IPC handlers in `ipc/chapter.ipc.ts` for chapter CRUD, content management, and related operations.
- Register chapter IPC module in `main.ts` for application-wide access.
- Enhance type definitions for chapter functionalities, improving code consistency.
- Refactor `ipc/book.ipc.ts` to include new `UpdateStoryData` interface and additional story update handler.
- Reorganize and reformat IPC handlers for improved readability and structure.
- Add missing type definitions for `StoryData`, `AddWorldElementData`, `SetAIGuideLineData`, and others.
- Simplify handler functions by enforcing consistent parameter usage and return types.
- Remove outdated comments, redundant logic, and placeholder TODOs.
- Delete `data.service.ts` and `offline-data.service.ts`, consolidating functionality into `LocalSystem`.
- Refactor book, character, and conversation operations to adopt unified, multilingual, and session-enabled IPC handlers in `LocalSystem`.
- Simplify redundant legacy methods, enhancing maintainability and consistency.
- Add `LocalSystem` with handlers for session retrieval (`userId`, `lang`) and error handling.
- Extend IPC handlers to support multilingual operations (`fr`, `en`) and session data injection
