feat(dcl): MxGateway StreamAlarms adapter (snapshot + live transitions, reconnecting)

Adds IAlarmSubscribableConnection to MxGatewayDataConnection (shared session-less
feed, ref-counted), IMxGatewayClient.RunAlarmStreamAsync over the package
StreamAlarmsAsync with internal reconnect, and MxGatewayAlarmMapper
(AlarmFeedMessage/OnAlarmTransitionEvent -> NativeAlarmTransition). Behavior
verified against a live gateway in Task 28; mapper unit-tested.

tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/Adapters/FakeMxGatewayClient.cs

@@ -58,6 +58,12 @@ public sealed class FakeMxGatewayClient : IMxGatewayClient, IMxGatewayClientFact
         ct.ThrowIfCancellationRequested(); // …or FaultEventLoop() faults it to simulate a stream break
     }
 
+    public Task RunAlarmStreamAsync(
+        string? alarmFilterPrefix,
+        Action<ZB.MOM.WW.ScadaBridge.Commons.Types.Alarms.NativeAlarmTransition> onTransition,
+        CancellationToken ct = default)
+        => Task.CompletedTask; // no alarm feed in the fake
+
     public ValueTask DisposeAsync() => ValueTask.CompletedTask;
 
     /// <summary>Simulate a stream break so the adapter raises Disconnected.</summary>