fix(historian): #674 review follow-ups — HistoryUpdate boot-window gate, node-level v1 refusal, plan-before-gate, UTC skew compare

- HistoryUpdate Primary gate now reads IHistoryUpdateRoleView (PrimaryGatePolicy.ShouldServeHistoryUpdate):
  the data-plane verdict but CLOSED until this node's first redundancy snapshot, so both pair nodes cannot
  accept in the pre-join boot window. Single nodes open on their own singleton's first snapshot; admin-only
  nodes register no view => no gate. DriverHostActor publishes it at every Primary-verdict publish point.
- SqlServer v1: the updater throws NotSupportedException on every arm; the node manager maps it to a
  node-level BadHistoryOperationUnsupported (was per-item under a Good node for UpdateData/DeleteAtTime).
  HistoryWrite bit still advertised on v1 (not knowable at materialise time) — documented.
- The update plan is evaluated before the Primary gate: an unservable request (Remove, IsDeleteModified,
  not historized, no updater) is BadHistoryOperationUnsupported off-Primary, not BadInvalidState.
- Local-kind SourceTimestamp converted to UTC before the future-skew compare and sent as UTC.
- Hosted-service wiring extracted to BuildHistoryUpdatePosture and tested (gate source, skew, clock).
- Docs: Historian.md (boot window, ordering, node-level v1, HistoryWrite bit), CLAUDE.md.

Co-Authored-By: Claude <noreply@anthropic.com>

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.Tests/StatusCodeOracleTests.cs

@@ -14,11 +14,6 @@ public sealed class StatusCodeOracleTests
         ((uint)Opc.Ua.AggregateBits.Calculated).ShouldBe(HistorianInfoBits.HistorianCalculated);
     }
 
-    /// <summary>#674: the v1-schema refusal code is the SDK's BadHistoryOperationUnsupported.</summary>
-    [Fact]
-    public void History_operation_unsupported_matches_the_SDK() =>
-        HistorianStatusCodes.BadHistoryOperationUnsupported.ShouldBe(Opc.Ua.StatusCodes.BadHistoryOperationUnsupported);
-
     [Fact]
     public void Interpolated_bits_match_the_SDK()
     {