fix: multiple bug fixes

isolated users, db backup, weird disconnect issues for long voice sessions,

toju-app/src/app/infrastructure/persistence/electron-database.service.ts

@@ -101,6 +101,11 @@ export class ElectronDatabaseService {
     return this.api.query<User | null>({ type: 'get-current-user', payload: {} });
   }
 
+  /** Retrieve the persisted current user ID without loading the full user. */
+  getCurrentUserId(): Promise<string | null> {
+    return this.api.query<string | null>({ type: 'get-current-user-id', payload: {} });
+  }
+
   /** Store which user ID is considered "current" (logged-in). */
   setCurrentUserId(userId: string): Promise<void> {
     return this.api.command({ type: 'set-current-user-id', payload: { userId } });