refactor(comm): retire ClusterClient naming after the gRPC cutover

Phase 4 of the ClusterClient -> gRPC migration deleted the Akka transports
but left the naming behind: `ClusterClientSiteAuditClient` was transport-
agnostic and worked unchanged, so it survived the deletion under a name
that now describes a transport the repo no longer has. Same for a scatter
of doc-comments still framing gRPC as "the new transport" beside an Akka
one that is gone.

Renames it to `SiteCommunicationAuditClient` (and its test file) and
rewrites the stale comments to describe the single transport that exists.
Also tightens CLAUDE.md: drops the self-describing directory listing and
the 27-component enumeration in favour of the non-obvious parts only.

Behaviour-neutral: names and prose only. Recorded as the Phase 4
follow-up in docs/plans/2026-07-22-clusterclient-to-grpc-plan.md.

src/ZB.MOM.WW.ScadaBridge.Commons/Messages/Instance/WaitForAttribute.cs

@@ -9,7 +9,7 @@ namespace ZB.MOM.WW.ScadaBridge.Commons.Messages.Instance;
 /// <b>Site-local only.</b> The optional <see cref="Predicate"/> is a non-serializable
 /// in-process delegate, so this message MUST flow only within a single site node's
 /// actor system (script execution → Instance Actor). It is never sent across the
-/// ClusterClient / gRPC boundary. The value-equality form (<see cref="TargetValueEncoded"/>)
+/// site↔central gRPC boundary. The value-equality form (<see cref="TargetValueEncoded"/>)
 /// would serialize, but the routed/inbound variant is deliberately out of scope here.
 /// </para>
 /// </summary>