Fix the database migration that adds `NOT NULL` clauses. It used
`INSERT INTO temp_x SELECT * from x;`, and the `*` returns the fields in
the order they are defined on the table. Since this might be different from
the order that the `INSERT INTO temp_x` expects, strange problems can
happen where columns get swapped (or constraints can fail on columns that
they should not fail for, because they got fed data from a different
column).
GORM has certain downsides:
- Code-first approach, where queries have to be translated to the Go code
required to execute them.
- GORM comes with its own SQLite implementation, which doesn't provide an
on-connect callback. This means that new connections cannot correctly
enable foreign key constraints, causing database consistency issues.
[SQLC](https://sqlc.dev/) solves these issues for us.
This commit doesn't fully replace GORM with SQLC, but introduces it for
a few queries. Once all queries have been converted, GORM can be removed
completely.
GORM Automigration created a separate `job_storage_infos` table (because
we used it wrong, to be fair), which is actually only used as an
embedded struct in the `jobs` table. This means this table itself can be
dropped.
Replace GORM's auto-migration with Goose. The latter uses hand-written
SQL queries to apply database schema changes, which is safer and easier to
understand than what GORM is doing.
