D2 follow-up: RTag2 doesn't cascade client identity to Trx

Tested hypothesis (1) from the plan: add RTag2(CM_EVENT tag id) to the
priming chain before AddNonStreamValuesBegin2.

Result:
- RTag2 itself succeeds: returns 25-byte response
  (01000000000100000001EE39C30EDCDC010100000000000000), no error buffer.
- But AddNonStreamValuesBegin2 still fails with the same
  04 33 00 00 00 (UnknownClient = 51) for all four handle formats.

So RTag2 on /Hist isn't the cross-service registration trigger we need
for /Trx. Plan doc updated with the result + next-session ordered
probes (try IStorageServiceContract, then IL walk CClientCommon,
then server-side decompile as last resort).

Probe orchestrator now also performs the RTag2 step so the test gives
one-shot diagnostic visibility of both calls.

178/178 tests pass.

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

tests/AVEVA.Historian.Client.Tests/HistorianWcfRevisionProbeTests.cs

@@ -47,6 +47,7 @@ public sealed class HistorianWcfRevisionProbeTests
         _output.WriteLine($"ClientHandle: {result.ClientHandle}");
         _output.WriteLine($"StorageSessionId: {result.StorageSessionId}");
         _output.WriteLine($"TrxInterfaceVersion: {result.TrxInterfaceVersion} (rc={result.TrxInterfaceVersionReturnCode}) ex={result.TrxInterfaceVersionException}");
+        _output.WriteLine($"RTag2Succeeded: {result.RTag2Succeeded} OutHex={result.RTag2OutHex} ErrHex={result.RTag2ErrorHex} Ex={result.RTag2Exception}");
         _output.WriteLine($"BeginSucceeded: {result.BeginSucceeded}");
         _output.WriteLine($"BeginTransactionId: {result.BeginTransactionId}");
         foreach (HistorianRevisionBeginAttempt attempt in result.BeginAttempts)