Remove SyncService and introduce context-based offline mode and state management

- Delete `SyncService` and its associated bidirectional synchronization logic.
- Add multiple context providers (`OfflineProvider`, `AlertProvider`, `LangContext`, `UserContext`, `SessionContext`, `WorldContext`, `SettingBookContext`) for contextual state management.
- Implement `SecureStorage` for OS-level secure data encryption and replace dependency on `SyncService` synchronization.
- Update localization files (`en.json`, `fr.json`) with offline mode and error-related strings.

context/WorldContext.ts

@@ -0,0 +1,10 @@
+import {WorldProps} from "@/lib/models/World";
+import {createContext, Dispatch, SetStateAction} from "react";
+
+export interface WorldContextProps {
+    worlds: WorldProps[];
+    setWorlds: Dispatch<SetStateAction<WorldProps[]>>;
+    selectedWorldIndex: number;
+}
+
+export const WorldContext = createContext<WorldContextProps>({} as WorldContextProps);