feat(historian): #674 HistoryUpdate posture — future-skew bound, Primary gate, SqlServer v1 accepted, QuestDB TTL pin

- HistoryUpdate items with SourceTimestamp > now + ServerHistorian:HistoryUpdateMaxFutureSkew
  (default 1 day, <=0 disables) => BadOutOfRange in the node manager (every backend, never sent);
  clock injected via OtOpcUaNodeManager.Clock (host TimeProvider).
- HistoryUpdate is Primary-only: off-Primary => BadInvalidState per node, after authorization,
  same IDriverPrimaryRoleSource verdict as the native-ack gate; HistoryRead ungated.
- SqlServer: base schema requirement back to v1; SupportsModifiedTrail (v>=2). On v1 with
  AutoCreateSchema=false: writes/reads/events/retention work, modified reads + HistoryUpdate =>
  BadHistoryOperationUnsupported with nothing sent, retention skips SampleModified, one Warning per boot.
- QuestDB integration test pinning wall-clock TTL (far-future row evicts only partitions older
  than the TTL by the wall clock), with a positive control.
- Docs: Historian.md, Configuration.md, security.md, CLAUDE.md (incl. QuestDB retry duplicates,
  #674.4 anonymous-readable trail with ACL off, #674.5 not implemented).

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

tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/NodeManagerHistoryReadModifiedTests.cs

@@ -203,6 +203,28 @@ public sealed class NodeManagerHistoryReadModifiedTests : IDisposable
         await host.DisposeAsync();
     }
 
+    /// <summary>
+    ///     #674: the HistoryUpdate Primary gate does not reach HistoryRead — a closed gate neither refuses a read nor is
+    ///     consulted by one (reads are served from any redundancy node), for modified and raw reads alike.
+    /// </summary>
+    [Fact]
+    public async Task The_history_update_primary_gate_is_not_consulted_for_reads()
+    {
+        var (host, nm, node, src) = await SetupAsync([Mod(1, 1, 1, HistoryModificationType.Update, "u", Epoch)]);
+        var consulted = 0;
+        nm.HistoryUpdatePrimaryGate = () => { Interlocked.Increment(ref consulted); return false; };
+
+        var modified = Read(nm, node, Epoch, Epoch.AddHours(1), max: 10, cp: null);
+        var raw = Read(nm, node, Epoch, Epoch.AddHours(1), max: 10, cp: null, modified: false);
+
+        modified.Error.StatusCode.Code.ShouldBe(StatusCodes.Good);
+        modified.Data!.DataValues.Count.ShouldBe(1);
+        raw.Error.StatusCode.Code.ShouldNotBe(StatusCodes.BadInvalidState);
+        src.Calls.ShouldBe(1);
+        consulted.ShouldBe(0);
+        await host.DisposeAsync();
+    }
+
     [Fact]
     public async Task A_backend_failure_is_isolated_to_its_node()
     {