Replace empty catch blocks with meaningful log statements in NatsServer,
NatsClient, and Program. Add WaitForReadyAsync() to NatsServer for
deterministic server startup. Replace Task.Delay/Thread.Sleep in tests
with PING/PONG protocol flush and SubscribeCoreAsync for reliable
subscription synchronization.
Validates the server against the official NATS .NET client library with
tests for basic pub/sub, wildcard (* and >) matching, fan-out to
multiple subscribers, and PING/PONG keepalive. All 5 tests pass without
requiring any server changes.