fix(dcl): ASCII-only connection actor names, guarded ActorOf, and gate rejection of colliding connection names (review 2026-10-21 lane A M2)

ConnectionActorNames.Sanitize (shared by the DCL manager and the site deploy
gate) keeps ASCII letters/digits and -_.*+:@&=,!~';() only. The manager fails a
connection whose sanitised name is invalid or already used (Error + site
event) instead of restarting; DeployCompileValidator rejects a config whose
connection names collide after sanitising.

src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Actors/DataConnectionManagerActor.cs

@@ -92,11 +92,37 @@ public class DataConnectionManagerActor : ReceiveActor
             command.FailoverRetryCount,
             _siteEventLogger));
 
-        // Sanitize name for Akka actor path (replace spaces and invalid chars)
-        var actorName = new string(command.ConnectionName
-            .Select(c => char.IsLetterOrDigit(c) || "-_.*$+:@&=,!~';()".Contains(c) ? c : '-')
-            .ToArray());
-        var actorRef = Context.ActorOf(props, actorName);
+        // Sanitize name for Akka actor path — ASCII only, never a leading '$' (see
+        // ConnectionActorNames). Two connection names can still sanitise to the same actor name
+        // ("PLC A" / "PLC-A"), and ActorOf throws synchronously on that (or on any name Akka
+        // refuses): that must fail THIS connection only, never escape to the supervisor and
+        // restart the whole manager with every live connection (review 2026-10-21, lane A M2).
+        var actorName = ConnectionActorNames.Sanitize(command.ConnectionName);
+        IActorRef actorRef;
+        try
+        {
+            if (!Context.Child(actorName).IsNobody())
+                throw new InvalidActorNameException(
+                    $"actor name [{actorName}] is already used by another connection");
+            actorRef = Context.ActorOf(props, actorName);
+        }
+        catch (InvalidActorNameException ex)
+        {
+            _log.Error(
+                "Connection {0} not created: its actor name '{1}' is invalid or already used by another " +
+                "connection ({2}). Rename the connection so its name differs in more than spaces/symbols.",
+                command.ConnectionName, actorName, ex.Message);
+            if (_siteEventLogger != null)
+            {
+                _ = _siteEventLogger.LogEventAsync(
+                    "connection", "Error", null, command.ConnectionName,
+                    $"Connection not created — runtime actor name '{actorName}' is invalid or already in use",
+                    ex.Message);
+            }
+            adapter.DisposeAsync().AsTask().ContinueWith(_ => { });
+            return;
+        }
+
         _connectionActors[command.ConnectionName] = actorRef;
 
         _log.Info("Created DataConnectionActor for {0} (protocol={1})",