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.AuditLog/ServiceCollectionExtensions.cs

@@ -144,8 +144,8 @@ public static class ServiceCollectionExtensions
 
         // ISiteStreamAuditClient: NoOp default. This binding remains correct for
         // central/test composition roots that have no SiteCommunicationActor.
-        // The real implementation is ClusterClientSiteAuditClient, which pushes
-        // audit telemetry to central over Akka ClusterClient via the site's
+        // The real implementation is SiteCommunicationAuditClient, which pushes
+        // audit telemetry to central via the site's
         // SiteCommunicationActor — the Host wires it directly into the
         // SiteAuditTelemetryActor's Props.Create call for site roles (it cannot
         // be a DI singleton because it needs the SiteCommunicationActor IActorRef,