Update app.py

app.py

@@ -8,7 +8,8 @@ import random
 from typing import Dict, List, Optional
 from performance_system import PerformanceAnalyzer
 from simulado_system import SimuladoSystem, CasoClinicoSystem
-from database.db_manager import RevalidaDatabase
+from database.db_manager import RevalidaDatabase  
+db = DatabaseManager()
 from performance_system import PerformanceAnalyzer, StudyMaterialGenerator, ProgressTracker
 
 class MotivationalCoach: