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/DebugView/DebugViewSnapshot.cs

@@ -19,8 +19,8 @@ namespace ZB.MOM.WW.ScadaBridge.Commons.Messages.DebugView;
 /// </para>
 /// <para>
 /// A new dedicated message type (<c>DebugViewInstanceNotFound</c>) was
-/// considered but rejected: the ClusterClient / ClusterClientReceptionist
-/// channel is typed on the request side and the bridge actor is already
+/// considered but rejected: the site↔central channel is typed on the request
+/// side and the bridge actor is already
 /// pattern-matching on <c>DebugViewSnapshot</c> for the initial-snapshot TCS
 /// in <c>DebugStreamService</c>.  Introducing a second reply type would require
 /// every consumer to handle an additional <c>Ask</c> result union — more change