- Replace `electron-store` with OS-level encrypted storage for secure token, userId, and language management in `LocalSystem` and `keyManager`.
- Add `init-user` IPC handler to initialize user data and manage encryption keys.
- Update login process to handle encrypted storage saving with fallback for macOS issues.
- Add offline warning component to `login/page.tsx` to handle first-time sync requirements.
- Remove `electron-store` and associated dependencies from `package.json` and `package-lock.json`.
- 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
