New lib/db/dbctl: SyncAuthorization runs after the DB starts (EnsureDatabaseRunning),
ensuring a LOGIN role + CONNECT grant per installed peer and revoking the stock
PUBLIC CONNECT grant on mTLS-armed databases; RevokeForService drops a peer's
CONNECT at uninstall. Admin executes over the in-container unix socket as
postgres (trust). Wired into ensureInfraRunning and UninstallContainer.
Includes unit tests + env-gated live integration test.