feat: completar fases 3 y 4 del roadmap mvp (gradebook, drag-and-drop, impersonacion) y actualizar README

backend/app/models/__init__.py

@@ -11,6 +11,7 @@ from .milestone import MilestoneType, AcademicMilestone, BASE_MILESTONE_TYPES
 from .audit_log import AuditLog
 from .enrollment import StudentEnrollment
 from .setting import SystemSetting
+from .grade import MilestoneGrade
 
 __all__ = [
     'User',
@@ -34,5 +35,6 @@ __all__ = [
     'BASE_MILESTONE_TYPES',
     'AuditLog',
     'StudentEnrollment',
-    'SystemSetting'
+    'SystemSetting',
+    'MilestoneGrade'
 ]