Update the default set of system fields for custom objects, to ensure
position is not nullabel and has a default value to 0
Steps to reproduce :
create a custom object,
send a POST request with body ```{position:null}```
the record should be created
After the change,
an error will be thrown
<img width="754" alt="Screenshot 2025-06-13 at 17 16 56"
src="https://github.com/user-attachments/assets/d40931f7-16cc-4b68-8dbb-deb0fa292be5"
/>
46d6e7a8bc