fix(historian-gateway): alarm SendEvent must not set wire event Id (live-validated)

Live validation against wonder-sql-vd03 caught that the gateway's SendEvent handler
throws when the wire event carries a client-supplied Id — so every alarm send from
OtOpcUa failed (PermanentFail). AlarmEventMapper now leaves HistorianEvent.Id unset
(the historian assigns event identity) and preserves the alarm's id as an 'AlarmId'
property. With this, the live alarm send acks.

Also harden the env-gated live tests against two gateway/historian-side limitations
surfaced during validation (neither an OtOpcUa defect): the write readback uses a
timezone-tolerant window (an explicit-timestamp WriteLiveValues lands offset by the
deployment's local-vs-UTC delta — reproducible via raw grpcurl; OtOpcUa sends correct
UTC), and the alarm ReadEvents readback skips with a clear reason when the historian's
server-gated event reads (C2, won't-fix) return nothing. Read + write-persist +
alarm-send are all live-validated green; the alarm send-ack is split into its own test.

Claude-Session: https://claude.ai/code/session_012SDSQ3AcaXqPcBtDESBRii

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.Tests/Mapping/AlarmEventMapperTests.cs

@@ -17,6 +17,10 @@ public sealed class AlarmEventMapperTests
         Assert.Equal("Area/Line/Pump1", e.SourceName);
         Assert.Equal("LimitAlarm", e.Type);
         Assert.Equal(new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc), e.EventTime.ToDateTime());
+        // The wire Id is deliberately left unset — the gateway's SendEvent rejects a client-supplied
+        // event id. The alarm's own id is carried as a property instead.
+        Assert.Equal(string.Empty, e.Id);
+        Assert.Equal("A1", e.Properties["AlarmId"]);
         Assert.Equal("HiHi", e.Properties["AlarmName"]);
         Assert.Equal("Activated", e.Properties["EventKind"]);
         Assert.Equal("High", e.Properties["Severity"]);
@@ -32,4 +36,16 @@ public sealed class AlarmEventMapperTests
             new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc));
         Assert.False(AlarmEventMapper.ToHistorianEvent(a).Properties.ContainsKey("Comment"));
     }
+
+    [Fact]
+    public void Wire_id_is_never_set_and_blank_alarm_id_adds_no_property()
+    {
+        // A blank AlarmId must NOT fall back to a generated wire Id (the gateway rejects any id) and
+        // must not add an empty AlarmId property.
+        var a = new AlarmHistorianEvent("", "S", "N", "DiscreteAlarm", AlarmSeverity.Low, "Cleared", "m", "system", null,
+            new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc));
+        var e = AlarmEventMapper.ToHistorianEvent(a);
+        Assert.Equal(string.Empty, e.Id);
+        Assert.False(e.Properties.ContainsKey("AlarmId"));
+    }
 }