[add]: ref_id and ref_model for transactions. And db session and rollback for transactions

app/models/loan.py

@@ -47,9 +47,7 @@ class Loan(db.Model):
 
         try:
             db.session.add(loan)
-            db.session.commit()
         except IntegrityError as err:
-            db.session.rollback()
             raise ValueError(f"Database integrity error: {err}")
         return loan
 
@@ -92,8 +90,7 @@ class Loan(db.Model):
         
         # Update loan status and the updated_at timestamp
         loan.status = status
-        
-        db.session.commit()
+
     
     def __repr__(self):
         return f'<Loan {self.id}>'