Finalize storage schema

[lusloher]

[Research ticket]

Design document: https://docs.google.com/document/d/1aoL5s-1X4AB7NKxSE-6hbOlTIueow2EitdnaEYcDaAA/edit

Establish the structure of the database in which the user data will be stored

Acceptance Criteria

• Research the schema

• Write out the def. of the database schema

[lusloher]

Link to subfeature: https://jinaai.productboard.com/feature-board/planning/features/7115703