Add apply/require startup policies and five database-only migration commands.
Provide standalone corestack-goose creation and reconciliation with fresh
provider-local Go registrations. Default optional --dir to the working directory.
Document the production boundary and source recovery requirements.
Closes#9
Add embedded SQL and provider-local Go migrations with slog logging and
Postgres session locking, returning Goose's Provider directly.
Cover timestamp and sequential versions, failure recovery, and concurrent
startup with SQLite and Postgres tests. Reuse page's Postgres CI service.
Document authoring conventions and the Go template compatibility gate.
Closes#7
Refs #9
end