Integrate session management, multilingual IPC handlers, and Book database operations

- 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

electron/preload.ts

@@ -9,8 +9,12 @@ contextBridge.exposeInMainWorld('electron', {
   setToken: (token: string) => ipcRenderer.invoke('set-token', token),
   removeToken: () => ipcRenderer.invoke('remove-token'),
 
+  // Language management
+  getLang: () => ipcRenderer.invoke('get-lang'),
+  setLang: (lang: 'fr' | 'en') => ipcRenderer.invoke('set-lang', lang),
+
   // Auth events
-  loginSuccess: (token: string) => ipcRenderer.send('login-success', token),
+  loginSuccess: (token: string, userId: string) => ipcRenderer.send('login-success', token, userId),
   logout: () => ipcRenderer.send('logout'),
 
   // Database operations