Address review: fail fast on store.Open/key-loader errors in test setup;
use t.Errorf+continue so every admin command is checked, not just the first.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Initialize a DB, drop EMCLI_ADMIN_KEY, attempt every admin command with
only EMCLI_KEY: each is refused and the DB is byte-for-byte unchanged.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>