build: bump nats.go to v1.52.0 and nats-server to v2.14.3

Both match the version entiredb already deploys. go-nuts's go.mod requirement is only a floor — consumers already float above it via MVS (entire-api on v1.51.0, entiredb on v1.52.0) — so this changes nothing those services build against. The point is go-nuts's own tests: they exercised the consumer lifecycle logic (Closed() channel semantics, the jetstream.ErrConnectionClosed / ErrMsgAlreadyAckd sentinels, the PullMaxMessages prefetch default) against nats.go v1.50.0 + embedded server v2.10.22, older than what production runs. Testing at least as new as the deployed version closes that gap; the full race suite passes unchanged, confirming none of that version-sensitive behavior shifted.

nats-server is a test-only dependency (embedded broker in the jsconsumer suite), so its bump affects go-nuts's tests only, not any consumer.