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/Site/Telemetry/ISiteStreamAuditClient.cs

@@ -6,9 +6,9 @@ namespace ZB.MOM.WW.ScadaBridge.AuditLog.Site.Telemetry;
 /// Mockable abstraction over the central site-audit push surface that
 /// <see cref="SiteAuditTelemetryActor"/> uses to forward <see cref="AuditEventBatch"/>
 /// payloads. The production implementation is
-/// <see cref="ClusterClientSiteAuditClient"/> — a ClusterClient-based client,
-/// wired in the Host for site roles, that forwards batches to central via the
-/// site's <c>SiteCommunicationActor</c>. Unit tests substitute via NSubstitute
+/// <see cref="SiteCommunicationAuditClient"/> — wired in the Host for site
+/// roles, it forwards batches to central via the site's
+/// <c>SiteCommunicationActor</c>. Unit tests substitute via NSubstitute
 /// against this interface so the actor never needs a live transport.
 /// </summary>
 public interface ISiteStreamAuditClient
@@ -36,8 +36,8 @@ public interface ISiteStreamAuditClient
     /// once central has acknowledged them.
     /// </summary>
     /// <remarks>
-    /// The production <see cref="ClusterClientSiteAuditClient"/> forwards over
-    /// the ClusterClient transport; the <see cref="NoOpSiteStreamAuditClient"/>
+    /// The production <see cref="SiteCommunicationAuditClient"/> forwards over
+    /// the site's central transport; the <see cref="NoOpSiteStreamAuditClient"/>
     /// DI default (used by central and test composition roots) returns an empty
     /// ack so no rows are flipped.
     /// </remarks>