SQLAlchemy schema needs to be updated with new constraints

#3939 introduced quite a few new NOT NULL constraints and then forgot to update the SQL schema for the API in `src/nominatim_api/sql/sqlalchemy_schema.py`. This file should be reviewed and updated to have the same definitions as `lib-sql`. Please be careful when doing this, some of the tables have a couple of columns are intentionally missing in this file. Thus the update should not add any new columns. _Note: make sure to read the [contribution guide lines on AI](https://github.com/osm-search/Nominatim/blob/master/CONTRIBUTING.md#using-ai-assisted-code-generators) before starting to work on this._