feat(abcip): final review I1 — node-level Drivers:AbCip:DefaultTransport

The old AdminUI cannot author the per-driver transport key (#576), so the
'pin before upgrading' recipe had no working path. A node-level appsetting
(env Drivers__AbCip__DefaultTransport) now supplies the default for AbCip
drivers with no key: explicit key > node default > compiled Native. Bound
and validated unconditionally (bad value fails host start); the driver
factory and the Test Connect probe both read it so they agree. AbCip.md
upgrade recipe rewritten around the key; Configuration.md documents it.
Also documents first-wins for AllowPacking/probe and host-alias throttles
(final review M6) and moves the status-bit note out of AbCip.md (M5).

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Server/ZB.MOM.WW.OtOpcUa.Host/Drivers/DriverFactoryBootstrap.cs

@@ -1,10 +1,12 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
 using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
 using ZB.MOM.WW.OtOpcUa.Core.Hosting;
 using ZB.MOM.WW.OtOpcUa.Core.Resilience;
 using ZB.MOM.WW.Secrets.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Host.Configuration;
 using ZB.MOM.WW.OtOpcUa.Runtime.Redundancy;
 
 namespace ZB.MOM.WW.OtOpcUa.Host.Drivers;
@@ -78,7 +80,8 @@ public static class DriverFactoryBootstrap
             // whole mechanism exists to prevent, and it would fail as a plant outage rather than as a
             // startup error.
             var primaryRoleSource = sp.GetRequiredService<IDriverPrimaryRoleSource>();
-            Register(registry, loggerFactory, secretResolver, primaryRoleSource, scriptRoot);
+            Register(registry, loggerFactory, secretResolver, primaryRoleSource, ResolveAbCipDefaultTransport(sp),
+                scriptRoot);
             return registry;
         });
         services.AddSingleton<IDriverFactory>(sp =>
@@ -140,7 +143,12 @@ public static class DriverFactoryBootstrap
     public static IServiceCollection AddOtOpcUaDriverProbes(this IServiceCollection services)
     {
         services.TryAddEnumerable(ServiceDescriptor.Singleton<IDriverProbe, ModbusProbe>());
-        services.TryAddEnumerable(ServiceDescriptor.Singleton<IDriverProbe, AbCipProbe>());
+        // Factory-built so the probe resolves an absent "transport" key to the SAME node default the driver
+        // factory uses (Drivers:AbCip:DefaultTransport, final review I1) — Test Connect probes the stack the
+        // driver would run. The generic factory overload keeps AbCipProbe as the implementation type, which
+        // TryAddEnumerable de-dups on.
+        services.TryAddEnumerable(ServiceDescriptor.Singleton<IDriverProbe, AbCipProbe>(
+            sp => new AbCipProbe(tagFactory: null, defaultTransport: ResolveAbCipDefaultTransport(sp))));
         services.TryAddEnumerable(ServiceDescriptor.Singleton<IDriverProbe, AbLegacyProbe>());
         services.TryAddEnumerable(ServiceDescriptor.Singleton<IDriverProbe, S7Probe>());
         services.TryAddEnumerable(ServiceDescriptor.Singleton<IDriverProbe, TwinCATProbe>());
@@ -155,6 +163,16 @@ public static class DriverFactoryBootstrap
         return services;
     }
 
+    /// <summary>
+    ///     The node-level AbCip default transport (<c>Drivers:AbCip:DefaultTransport</c>, bound + validated in
+    ///     Program.cs). A container without the options bound (test graphs) gets the compiled default.
+    /// </summary>
+    /// <param name="sp">The service provider.</param>
+    /// <returns>The transport an AbCip driver with no <c>transport</c> key runs on.</returns>
+    internal static Driver.AbCip.AbCipTransport ResolveAbCipDefaultTransport(IServiceProvider sp) =>
+        sp.GetService<IOptions<AbCipDriverDefaultsOptions>>()?.Value.ResolveDefaultTransport()
+            ?? Driver.AbCip.AbCipTransportResolver.Default;
+
     /// <summary>
     ///     Invoke every cross-platform driver's <c>Register</c> extension. New driver assemblies
     ///     get added here — one line per type. ShouldStub() in <c>DriverInstanceActor</c> still
@@ -166,9 +184,10 @@ public static class DriverFactoryBootstrap
         ILoggerFactory? loggerFactory,
         ISecretResolver secretResolver,
         IDriverPrimaryRoleSource primaryRoleSource,
+        Driver.AbCip.AbCipTransport abCipDefaultTransport,
         ZB.MOM.WW.OtOpcUa.Core.Scripting.ScriptRootLogger? scriptRoot = null)
     {
-        Driver.AbCip.AbCipDriverFactoryExtensions.Register(registry, loggerFactory);
+        Driver.AbCip.AbCipDriverFactoryExtensions.Register(registry, loggerFactory, abCipDefaultTransport);
         Driver.AbLegacy.AbLegacyDriverFactoryExtensions.Register(registry, loggerFactory);
         Driver.Calculation.CalculationDriverFactoryExtensions.Register(registry, loggerFactory, scriptRoot);
         Driver.FOCAS.FocasDriverFactoryExtensions.Register(registry);