Wire SDK for remote-TCP end to end; live-verify RemoteTcpIntegrated

Executes docs/plans/tcp-connection-validation.md. Full read-only SDK
surface now works against a remote AVEVA Historian over Net.TCP with
Windows transport authentication. 124/124 tests pass; the +10 new live
integration tests in RemoteTcpIntegrationTests.cs are gated by
HISTORIAN_REMOTE_TCP_HOST + HISTORIAN_REMOTE_TCP_TAG.

Two SDK bugs found while executing the plan:

1. Historian2020ProtocolDialect.ReadRawAsync / ReadAggregateAsync /
   ReadAtTimeAsync / ReadEventsAsync had explicit
   `if (_options.Transport != HistorianTransport.LocalPipe) return Missing<T>`
   guards. These were a guardrail from before the orchestrators handled
   TCP; the orchestrators have always used CreateBindingPair(options)
   which dispatches on transport correctly. Gates removed.

2. HistorianWcfStatusClient and HistorianWcfEventOrchestrator hardcoded
   HistorianWcfBindingFactory.CreatePipeEndpointAddress for the auxiliary
   services (Stat, Trx, Retr). Worked for LocalPipe; for TCP it produced
   an EndpointAddress with scheme net.pipe attached to a TCP binding
   (channel factory rejected the URI). Worse, when only the endpoint was
   transport-aware, the binding still requested a Windows-transport-
   security upgrade that the Stat endpoint over TCP doesn't support
   (auxiliaries don't repeat the auth — the Hist session is already
   authenticated). Added two helpers:
   - HistorianWcfBindingFactory.CreateAuxiliaryEndpointAddress(options, name)
     -> net.pipe for LocalPipe, net.tcp for remote
   - HistorianWcfBindingFactory.CreateAuxiliaryBinding(options)
     -> NamedPipe for LocalPipe, plain MdasNetTcpBinding for remote
   Both call sites updated.

Live verification against the remote (probed previously in prior
sessions; reachability re-confirmed today):
- ProbeAsync over RemoteTcpIntegrated and RemoteTcpCertificate
- ReadRawAsync (8 samples returned for SysTimeSec)
- ReadAggregateAsync (TimeWeightedAverage, 1-min cycle, 10-min window)
- ReadAtTimeAsync (3 timestamps)
- BrowseTagNamesAsync (finds the test tag)
- GetTagMetadataAsync (full metadata populated)
- ReadEventsAsync (chain runs without throwing)
- GetConnectionStatusAsync (ConnectedToServer=true)
- GetSystemParameterAsync (HistorianVersion="20,0,000,000")

The default 'NT SERVICE\aahClientAccessPoint' SPN turned out to work
for the remote too — discovery workstream A (SPN-finding) was not
needed in practice.

README and the TCP plan doc updated to reflect the executed status.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/AVEVA.Historian.Client/Wcf/HistorianWcfStatusClient.cs

@@ -36,12 +36,13 @@ internal static class HistorianWcfStatusClient
     {
         Guid contextKey = Guid.NewGuid();
         var (histBinding, histEndpoint, _, _) = HistorianWcfBindingFactory.CreateBindingPair(options);
-        EndpointAddress statusEndpoint = HistorianWcfBindingFactory.CreatePipeEndpointAddress(options.Host, HistorianWcfServiceNames.Status);
+        Binding statusBinding = HistorianWcfBindingFactory.CreateAuxiliaryBinding(options);
+        EndpointAddress statusEndpoint = HistorianWcfBindingFactory.CreateAuxiliaryEndpointAddress(options, HistorianWcfServiceNames.Status);
 
         string? value = null;
         HistorianWcfAuthChainHelper.OpenAuthenticatedConnection(
             options, histBinding, histEndpoint, contextKey, CancellationToken.None,
-            additionalSetup: (_, context) => value = QuerySystemParameter(histBinding, statusEndpoint, context.ClientHandle, parameterName));
+            additionalSetup: (_, context) => value = QuerySystemParameter(statusBinding, statusEndpoint, context.ClientHandle, parameterName));
         return value;
     }