M3 R3.2 SHIPPED: AddHistoricalValuesAsync — historical backfill writes over gRPC (live-validated)

Public HistorianClient.AddHistoricalValuesAsync(tag, values) inserts non-streamed original
(backfill) values for an existing tag over the 2023 R2 gRPC front door. The pure-managed SDK
wrote a value and read it back live (gated test AddHistoricalValuesAsync_OverGrpc_WritesAndReadsBack
PASSED against the real server).

- HistorianGrpcHistoricalWriteOrchestrator: write-enabled (0x401) session ->
  RetrievalService.GetTagInfosFromName (resolves the per-tag GUID = the tag-info TypeId, and
  registers the tag on the session) -> HistoryService.AddStreamValues("ON" buffer) per sample.
- HistorianHistoricalValue (public record: TimestampUtc, Value, OpcQuality=192).
- gRPC-only: non-RemoteGrpc transports throw ProtocolEvidenceMissingException (the 2020 WCF
  non-streamed write is architecturally blocked, D2).
- Float value encoding only (the captured type); other types rejected by the serializer.

275 unit tests pass; the new gated live write/read-back test is green against the 2023 R2 server.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B6mcaT2PjRFKcogzp9UkfC

src/AVEVA.Historian.Client/Models/HistorianHistoricalValue.cs

@@ -0,0 +1,11 @@
+namespace AVEVA.Historian.Client.Models;
+
+/// <summary>
+/// A single historical (backfill) value to insert via
+/// <see cref="HistorianClient.AddHistoricalValuesAsync"/>. The historian stores the value against
+/// the tag at <paramref name="TimestampUtc"/> as original (non-streamed) data.
+/// </summary>
+/// <param name="TimestampUtc">The value timestamp (UTC). Treated as UTC if unspecified-kind.</param>
+/// <param name="Value">The numeric value. Captured/supported for Float tags today.</param>
+/// <param name="OpcQuality">OPC quality; defaults to 192 (good).</param>
+public sealed record HistorianHistoricalValue(DateTime TimestampUtc, double Value, ushort OpcQuality = 192);