CultNetDatabaseServerOptions.RemoteWriteAuthority is asked once per received
write, after the schema resolves and before the shard does; none configured
refuses every remote write; an authority that throws refuses and is logged.
A refusal applies, publishes, logs and forwards nothing. The host's own
CultNetDatabase.ApplyPutAsync/ApplyDeleteAsync ask no remote authority.
Existing server tests whose subject is not the grant pass a test-local
granting authority.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
