feat(adminui): Transport dropdown on AbCip/AbLegacy driver forms (live-verified on docker-dev)

- AbCip/AbLegacy driver forms gain a Transport InputSelect; FromOptions/ToOptions now carry
  Transport, so saving any other field no longer silently reverts Native to libplctag.
- Both drivers log the constructed transport once per init.
- AbCip factory now takes the host ILoggerFactory (it ran on NullLogger in production, hiding
  every AbCip log line); DriverFactoryBootstrap passes it.
- Gate results: AdminUI /run (T19) native, inverted (dead port) and libplctag legs.

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDriver.cs

@@ -70,6 +70,7 @@ public sealed class AbLegacyDriver : IDriver, IReadable, IWritable, ITagDiscover
         _driverInstanceId = driverInstanceId;
         // Chosen once here and held across ReinitializeAsync (Shutdown+Initialize): a changed
         // Transport in a reinit config is inert; a deploy recreates the instance instead.
+        _transport = options.Transport;
         _tagFactory = tagFactory ?? (options.Transport == AbLegacyTransport.Native
             ? new NativeAbLegacyTagFactory()
             : new LibplctagLegacyTagFactory());
@@ -92,6 +93,10 @@ public sealed class AbLegacyDriver : IDriver, IReadable, IWritable, ITagDiscover
     /// <summary>The tag factory chosen at construction; exposed so tests can pin transport selection.</summary>
     internal IAbLegacyTagFactory TagFactory => _tagFactory;
 
+    // The transport chosen at construction (see the ctor); logged at every init so an operator can tell
+    // from the node log which stack serves this instance.
+    private readonly AbLegacyTransport _transport;
+
     /// <summary>Upper bound on the poll-loop failure backoff — adopts the S7-proven 30 s cap fleet-wide (05/STAB-8).</summary>
     private static readonly TimeSpan PollBackoffCap = TimeSpan.FromSeconds(30);
 
@@ -129,6 +134,9 @@ public sealed class AbLegacyDriver : IDriver, IReadable, IWritable, ITagDiscover
     public Task InitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
     {
         _health = new DriverHealth(DriverState.Initializing, null, null);
+        _logger.LogInformation(
+            "AbLegacy driver {DriverInstanceId} initializing: transport={Transport} tagFactory={TagFactory}",
+            _driverInstanceId, _transport, _tagFactory.GetType().Name);
         try
         {
             // #516: re-parse the supplied DriverConfig so a config change delivered through the IDriver