Problem

Wolverine.Nats fails to send any scheduled message over NATS JetStream native scheduling (NATS Server 2.12+). The transport publishes the scheduling control message to the same subject it sets as the Nats-Schedule-Target header, but NATS requires the control message to be published to a subject different from the target. The server rejects the publish:

{"error":{"code":400,"err_code":10190,"description":"message schedules target is invalid"}}

The send throws, nothing is materialized, and the consumer never receives the message.

Fix

JetStreamPublisher now keeps Nats-Schedule-Target = the real destination subject (where the listener's exact-FilterSubject consumer reads and the server materializes the message at fire time) and publishes the control message to a derived subject:

• Derived subject defaults to <subject>.scheduled.
• Configurable per endpoint via UseScheduleSubjectSuffix(...).
• Both the target and the schedule subject must be covered by the same stream → use a prefix.> filter (a single-token * / exact-subject filter will not cover the derived subject).
• An empty/whitespace suffix falls back to .scheduled, so the control subject can never collapse onto the target again.

Tests

• schedule_send_over_native_jetstream_scheduling — drives the native path by putting .UseJetStream(stream) on the publishing endpoint. Times out before the fix, passes after. Asserts the native path is engaged (not the durable fallback). Skips on NATS < 2.12.
• overridden_suffix_is_used_for_native_scheduling — provisions the stream with explicit subjects covering only the target and the .override-scheduled subject (default .scheduled deliberately not covered), so delivery only succeeds if the configured suffix is actually applied.