Extracts the union of authd's three CLI scripts (db-migrate.ts,
db-status.ts, db-stamp.ts) into one wrapper. Consumers wire a ~5-line shim
that injects their own openDb / migrationsDir / config-loading logic. The
wrapper returns an exit code rather than calling process.exit, which keeps
it testable via PassThrough stream capture.
Forward-only SQLite migration runner lifted from authd (src/db/migrate.ts,
PR #14 / merge ced21ab) and parameterized for cross-project use. The single
deliberate API change vs. authd's source: the previously-hardcoded
GENESIS_PROBE_TABLE = 'users' is now an ApplyOptions.genesisProbeTable?: string
option (default 'users').
