With Ibis how to ALTER TABLE to add columns, foreign keys, constraints or indexes?

[Mevrael]

Let say I have a simple model/schema, and I am creating a new sqlite DB table:

@dataclass
class User:
    id: int
    name: str
    email: str
    age: int

con = ibis.sqlite.connect('test.db')

# Create table first time in the initial migration
users = con.create_table('user', schema=User)

# Later read the table from another file
users = con.table('user')

I've looked into mutate(), but seems it can only create virtual columns that must rely on expression using an existing column.

Questions:

1. How would I add a new column in DB, do a kinda migration, to an existing table and data? For example, how would I add a new is_admin: bool = False column with a default value? I.e. ALTER TABLE user ADD COLUMN is_admin BOOLEAN DEFAULT FALSE;

2. And how would I add a foreign key or constrain, or just an index to optimize specific table in the DB/DWH?