Fix refresh token naming inconsistency in login response

src/services/authService.js

@@ -50,7 +50,7 @@ class AuthService {
       userId: user.id
     });
 
-    return { encrypted_master_key: user.encrypted_master_key, access_token, refreshToken: randomToken };
+    return { encrypted_master_key: user.encrypted_master_key, access_token, refresh_token: randomToken };
   }
 
   // REFRESH: Intercambia un Refresh Token válido por un nuevo Access Token limpio