feat(migrate): add lifecycle commands and standalone authoring (#18)

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

migrate/lifecycle/testdata/migrations/00001_first.sql

@@ -0,0 +1,4 @@
+-- +goose Up
+CREATE TABLE events (id INTEGER PRIMARY KEY);
+-- +goose Down
+DROP TABLE events;