feat(migrate): configure embedded Goose providers

Use provider-local SQL and Go migrations, injected slog logging, and PostgreSQL session locking. Exercise timestamp migration flows and failures with SQLite and PostgreSQL, including concurrent startup, and require PostgreSQL integration coverage in CI.

Refs #7

migrate/testdata/failure/20261027114500_broken.sql

@@ -0,0 +1,6 @@
+-- +goose Up
+INSERT INTO migration_events (version) VALUES (20261027114500);
+INSERT INTO missing_migration_table (version) VALUES (20261027114500);
+
+-- +goose Down
+DELETE FROM migration_events WHERE version = 20261027114500;