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.

electron/ipc/book.ipc.ts

@@ -1,6 +1,6 @@
 import { ipcMain } from 'electron';
 import { createHandler } from '../database/LocalSystem.js';
-import Book from '../database/models/Book.js';
+import Book, {CompleteBook, SyncedBook} from '../database/models/Book.js';
 import type { BookProps, GuideLine, GuideLineAI, Act, Issue, WorldProps } from '../database/models/Book.js';
 import Chapter from '../database/models/Chapter.js';
 import type { ChapterProps } from '../database/models/Chapter.js';
@@ -88,6 +88,10 @@ interface SetAIGuideLineData {
     themes: string;
 }
 
+interface GetGuidelineData {
+    id: string;
+}
+
 // GET /books - Get all books
 ipcMain.handle('db:book:books', createHandler<void, BookProps[]>(
         async function(userId: string, _body: void, lang: 'fr' | 'en'):Promise<BookProps[]> {
@@ -96,6 +100,20 @@ ipcMain.handle('db:book:books', createHandler<void, BookProps[]>(
     )
 );
 
+// GET /books/synced - Get all synced books
+ipcMain.handle('db:books:synced', createHandler<void, SyncedBook[]>(
+        async function(userId: string, _body: void, lang: 'fr' | 'en'):Promise<SyncedBook[]> {
+            return await Book.getSyncedBooks(userId, lang);
+        })
+);
+
+// POST /book/sync/save - Save complete book
+ipcMain.handle('db:book:syncSave', createHandler<CompleteBook, boolean>(
+        async function(userId: string, data: CompleteBook, lang: 'fr' | 'en'):Promise<boolean> {
+            return await Book.saveCompleteBook(userId, data, lang);
+        })
+);
+
 // GET /book/:id - Get single book
 ipcMain.handle('db:book:bookBasicInformation', createHandler<string, BookProps>(
         async function(userId: string, bookId: string, lang: 'fr' | 'en'):Promise<BookProps> {
@@ -113,11 +131,7 @@ ipcMain.handle('db:book:updateBasicInformation', createHandler<UpdateBookBasicDa
 );
 
 // GET /book/guide-line - Get guideline
-interface GetGuidelineData {
-    id: string;
-}
-ipcMain.handle(
-    'db:book:guideline:get',
+ipcMain.handle('db:book:guideline:get',
     createHandler<GetGuidelineData, GuideLine | null>(async function(userId: string, data: GetGuidelineData, lang: 'fr' | 'en') {
             return await Book.getGuideLine(userId, data.id, lang);
         }