CAT-D7: distribution's whole-module integration test against a real bus

The program had no test that runs it whole. This one starts run() on a nats-server of its own, with the registry
container faked on the loopback and node_haves and manifest-reads answered on their call subjects: an away node holds
both windows open, its return closes them, each closing said once on distribution.events, a direct write is then
refused, reads stay open, the health check answers through the program's port, and a waiter on published wakes on
none of the windows' events.

Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig

modules/distribution/go.mod

@@ -8,9 +8,15 @@ require (
 )
 
 require (
+	github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op // indirect
+	github.com/google/go-tpm v0.9.8 // indirect
 	github.com/klauspost/compress v1.20.0 // indirect
+	github.com/minio/highwayhash v1.0.4 // indirect
+	github.com/nats-io/jwt/v2 v2.8.1 // indirect
+	github.com/nats-io/nats-server/v2 v2.11.17 // indirect
 	github.com/nats-io/nkeys v0.4.16 // indirect
 	github.com/nats-io/nuid v1.0.1 // indirect
 	golang.org/x/crypto v0.57.0 // indirect
 	golang.org/x/sys v0.48.0 // indirect
+	golang.org/x/time v0.15.0 // indirect
 )