Add automated migrations

[LiquidLemon]

We need introduce some migration tooling to be able to safely modify the database schema. The official tooling is lacking, so here are some options to consider:

• https://github.com/klen/peewee_migrate
• https://github.com/aachurin/peewee_migrations

Or we could even use some generic SQL tool. I know Flyway used to be popular but they try to sell the paid versions so hard it's difficult to even find the docs on their website now :(

[LiquidLemon]

https://github.com/ariga/atlas seems really interesting because it supports generating migrations from SQL schema which means we don't need to rely on Peewee support 👀

[not7cd]

Atlas looks cool 😎. Maybe we should use it?