feat(dcl): OPC UA Alarms & Conditions adapter (event subscription + ConditionRefresh)

Adds IAlarmSubscribableConnection to OpcUaDataConnection, IOpcUaClient alarm
subscription methods, and RealOpcUaClient A&C event monitored-item +
EventFilter + ConditionRefresh snapshot, mapping fields via OpcUaAlarmMapper.
Behavior verified against a live A&C server in Task 28; mapper unit-tested.

src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/OpcUaDataConnection.cs

@@ -17,7 +17,7 @@ namespace ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Adapters;
 /// - Read/Write → Read/Write service calls
 /// - Quality → OPC UA StatusCode mapping
 /// </summary>
-public class OpcUaDataConnection : IDataConnection, IBrowsableDataConnection
+public class OpcUaDataConnection : IDataConnection, IBrowsableDataConnection, IAlarmSubscribableConnection
 {
     private readonly IOpcUaClientFactory _clientFactory;
     private readonly ILogger<OpcUaDataConnection> _logger;
@@ -174,6 +174,27 @@ public class OpcUaDataConnection : IDataConnection, IBrowsableDataConnection
             cancellationToken);
     }
 
+    /// <inheritdoc />
+    public async Task<string> SubscribeAlarmsAsync(
+        string sourceReference, string? conditionFilter,
+        AlarmTransitionCallback callback, CancellationToken cancellationToken = default)
+    {
+        EnsureConnected();
+        // The client maps OPC UA A&C event fields → NativeAlarmTransition via
+        // OpcUaAlarmMapper and replays a snapshot on (re)subscribe.
+        return await _client!.CreateAlarmSubscriptionAsync(
+            sourceReference, conditionFilter,
+            transition => callback(transition),
+            cancellationToken);
+    }
+
+    /// <inheritdoc />
+    public async Task UnsubscribeAlarmsAsync(string subscriptionId, CancellationToken cancellationToken = default)
+    {
+        if (_client != null)
+            await _client.RemoveAlarmSubscriptionAsync(subscriptionId, cancellationToken);
+    }
+
     /// <inheritdoc />
     public async Task UnsubscribeAsync(string subscriptionId, CancellationToken cancellationToken = default)
     {