Remove DataService and OfflineDataService, refactor book and character operations to use streamlined handlers in LocalSystem

- 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.

electron/preload.ts

@@ -1,36 +1,34 @@
 const { contextBridge, ipcRenderer } = require('electron');
 
-// Exposer des APIs sécurisées au renderer process
+/**
+ * Exposer des APIs sécurisées au renderer process
+ * Utilise invoke() générique pour tous les appels IPC
+ */
 contextBridge.exposeInMainWorld('electron', {
+  // Platform info
   platform: process.platform,
 
-  // Token management
+  // Generic invoke method - use this for all IPC calls
+  invoke: (channel: string, ...args: any[]) => ipcRenderer.invoke(channel, ...args),
+
+  // Token management (shortcuts for convenience)
   getToken: () => ipcRenderer.invoke('get-token'),
   setToken: (token: string) => ipcRenderer.invoke('set-token', token),
   removeToken: () => ipcRenderer.invoke('remove-token'),
 
-  // Language management
+  // Language management (shortcuts for convenience)
   getLang: () => ipcRenderer.invoke('get-lang'),
   setLang: (lang: 'fr' | 'en') => ipcRenderer.invoke('set-lang', lang),
 
-  // Auth events
+  // Auth events (use send for one-way communication)
   loginSuccess: (token: string, userId: string) => ipcRenderer.send('login-success', token, userId),
   logout: () => ipcRenderer.send('logout'),
 
-  // Database operations
+  // Encryption key management (shortcuts for convenience)
   generateEncryptionKey: (userId: string) => ipcRenderer.invoke('generate-encryption-key', userId),
   getUserEncryptionKey: (userId: string) => ipcRenderer.invoke('get-user-encryption-key', userId),
   setUserEncryptionKey: (userId: string, encryptionKey: string) => ipcRenderer.invoke('set-user-encryption-key', userId, encryptionKey),
+
+  // Database initialization (shortcut for convenience)
   dbInitialize: (userId: string, encryptionKey: string) => ipcRenderer.invoke('db-initialize', userId, encryptionKey),
-  dbGetBooks: () => ipcRenderer.invoke('db-get-books'),
-  dbGetBook: (bookId: string) => ipcRenderer.invoke('db-get-book', bookId),
-  dbSaveBook: (book: any, authorId?: string) => ipcRenderer.invoke('db-save-book', book, authorId),
-  dbDeleteBook: (bookId: string) => ipcRenderer.invoke('db-delete-book', bookId),
-  dbSaveChapter: (chapter: any, bookId: string, contentId?: string) => ipcRenderer.invoke('db-save-chapter', chapter, bookId, contentId),
-  dbGetCharacters: (bookId: string) => ipcRenderer.invoke('db-get-characters', bookId),
-  dbSaveCharacter: (character: any, bookId: string) => ipcRenderer.invoke('db-save-character', character, bookId),
-  dbGetConversations: (bookId: string) => ipcRenderer.invoke('db-get-conversations', bookId),
-  dbSaveConversation: (conversation: any, bookId: string) => ipcRenderer.invoke('db-save-conversation', conversation, bookId),
-  dbGetSyncStatus: () => ipcRenderer.invoke('db-get-sync-status'),
-  dbGetPendingChanges: (limit?: number) => ipcRenderer.invoke('db-get-pending-changes', limit),
 });