Add BooksSyncContext, refine database schema, and enhance synchronization support

- Introduce `BooksSyncContext` for managing book synchronization states (server-only, local-only, to-sync, etc.).
- Remove `UserContext` and related dependencies.
- Refine localization strings (`en.json`) with sync-related updates (e.g., "toSyncFromServer", "toSyncToServer").
- Extend database schema with additional tables and fields for syncing books, chapters, and related entities.
- Add `last_update` fields and update corresponding repository methods to support synchronization logic.
- Enhance IPC handlers with stricter typing, data validation, and sync-aware operations.

context/BooksSyncContext.ts

@@ -0,0 +1,22 @@
+import {SyncedBook} from "@/lib/models/SyncedBook";
+import {Context, createContext} from "react";
+
+export type SyncType = 'server-only' | 'local-only' | 'to-sync-from-server' | 'to-sync-to-server' | 'synced'
+
+export interface BooksSyncContextProps {
+    serverSyncedBooks:SyncedBook[];
+    localSyncedBooks:SyncedBook[];
+    booksToSyncFromServer:SyncedBook[];
+    booksToSyncToServer:SyncedBook[];
+    serverOnlyBooks:SyncedBook[];
+    localOnlyBooks:SyncedBook[];
+}
+
+export const BooksSyncContext:Context<BooksSyncContextProps> = createContext<BooksSyncContextProps>({
+    serverSyncedBooks:[],
+    localSyncedBooks:[],
+    booksToSyncFromServer:[],
+    booksToSyncToServer:[],
+    serverOnlyBooks:[],
+    localOnlyBooks:[]
+})