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.Communication/Actors/SiteAlarmAggregatorActor.cs

@@ -536,7 +536,7 @@ public sealed class SiteAlarmAggregatorActor : ReceiveActor, IWithTimers
         if (_retryCount > MaxRetries)
         {
             // Give up the stream, but do NOT stop the aggregator: the periodic reconcile
-            // still refreshes the cache from ClusterClient snapshots, so the page keeps a
+            // still refreshes the cache from site snapshots, so the page keeps a
             // (slower) live-ish view rather than going dark. A later reconcile-triggered
             // reconnect is not attempted here; the stream is simply left down.
             _log.Error("Site-alarm gRPC stream for {0} exceeded max retries ({1}); leaving stream down, " +