feat: credit system (and refactor: migrate to toasty)

[ChristianBeilschmidt]

Database for migrations needs table

CREATE TABLE IF NOT EXISTS __toasty_migrations (
    id BIGINT PRIMARY KEY,
    name TEXT NOT NULL,
    applied_at TIMESTAMP NOT NULL
)

and data

INSERT INTO __toasty_migrations (id, name, applied_at) VALUES (540260129757782932, 0000_initial.sql, NOW())

[coveralls]

Coverage is 86.28% — feat/credits into main. No base build found for main.