Add 2023 R2 gRPC transport (RemoteGrpc) reusing native byte payloads

Stands up HistorianTransport.RemoteGrpc end-to-end for the read path,
built on the recovered 2023 R2 gRPC contract (gRPC-Web/HTTP-1.1, port
32565, gzip). The opaque protobuf `bytes` fields carry the SAME native
binary payloads as the 2020 WCF/MDAS path, so the proven serializers and
parsers are reused unchanged.

- Grpc/Protos/*.proto: 6 protoc-validated contracts recovered from
  embedded FileDescriptors (authoritative, not guessed).
- Grpc/HistorianGrpcChannelFactory: GrpcWebHandler/HTTP-1.1 channel,
  ResolvePort/ResolveAddress, optional TLS + gzip.
- Grpc/HistorianGrpcReadOrchestrator: mirrors the WCF read chain over
  gRPC; auth uses HistoryService.ExchangeKey (the gRPC ValCl op).
- Wcf/HistorianNativeHandshake: transport-agnostic Open2 request builder
  + SSPI/Negotiate token loop + response decode, shared by WCF and gRPC.
- Op map (2020 -> gRPC): ValCl->ExchangeKey, Open2->OpenConnection,
  StartQuery2->StartQuery, GetNextQueryResultBuffer2->GetNextQueryResultBuffer.
- HistorianClientOptions: DefaultGrpcPort=32565, GrpcUseTls.
- csproj: Google.Protobuf, Grpc.Net.Client(.Web), Grpc.Tools codegen.

Not yet live-verified against a 2023 R2 server: ExchangeKey is the first
thing to revisit if a live server rejects the handshake; the inner byte
payloads are the proven 2020 protocol. Gated live test via
HISTORIAN_GRPC_HOST. 188 unit tests green; build clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/AVEVA.Historian.Client/AVEVA.Historian.Client.csproj

@@ -12,6 +12,23 @@
     <PackageReference Include="System.ServiceModel.NetTcp" Version="10.0.652802" />
   </ItemGroup>
 
+  <!-- 2023 R2 gRPC transport (RemoteGrpc). Pure-managed: Grpc.Net.Client +
+       Google.Protobuf. Grpc.Tools is build-only (PrivateAssets=all) and
+       generates the client stubs from the recovered contract under Grpc/Protos. -->
+  <ItemGroup>
+    <PackageReference Include="Google.Protobuf" Version="3.24.4" />
+    <PackageReference Include="Grpc.Net.Client" Version="2.58.0" />
+    <PackageReference Include="Grpc.Net.Client.Web" Version="2.58.0" />
+    <PackageReference Include="Grpc.Tools" Version="2.59.0">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+
+  <ItemGroup>
+    <Protobuf Include="Grpc\Protos\*.proto" GrpcServices="Client" ProtoRoot="Grpc\Protos" />
+  </ItemGroup>
+
   <ItemGroup>
     <AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleToAttribute">
       <_Parameter1>AVEVA.Historian.Client.Tests</_Parameter1>