Add the ability to contributors to easily seed the datbase

[Saterz]

Is your feature request related to a problem? Please describe.
Right now if someone wants to contribute to the app, they necessarily need to spin up a local Supabase instance. But there is no default data and they find themselves forced to populate the database by hand which adds friction and is not a good user experience.

Describe the solution you'd like
To either populate the database programmatically with @snaplet/seed or alternatives. Or directly commit a supabase/seed.sql file.

Describe alternatives you've considered
None

Additional context
@snaplet/seed seems to be abandoned