feat(secrets): G-2a secret: arm on GalaxySecretRef via ISecretResolver (Task 7)

Add a secret:NAME arm to GalaxySecretRef.ResolveApiKey that resolves the Galaxy
gateway API key through the shared ISecretResolver — fail-closed if the secret is
absent (never falls through to the cleartext literal arm), retiring the dev:/literal
in-DB path for production. Because GetAsync is async the method becomes
ResolveApiKeyAsync; the await cascade threads ISecretResolver by ctor injection into
GalaxyDriver + GalaxyDriverBrowser and (since GalaxyDriver is built by a static
factory closure, not DI) through GalaxyDriverFactoryExtensions + DriverFactoryBootstrap
(which pulls the real resolver from the service provider — registered unconditionally
in Slice 1). A NullSecretResolver null-object backs the parse-only/test paths only;
the runtime path always gets the real resolver (verified end-to-end).

TDD: 3 new secret:-arm tests (resolve / fail-closed-on-absent / no-literal-warning)
RED without the arm, GREEN with it; 338 Galaxy tests pass; no sync-over-async.

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Browser/GalaxyDriverBrowser.cs

@@ -5,6 +5,7 @@ using Microsoft.Extensions.Logging.Abstractions;
 using ZB.MOM.WW.MxGateway.Client;
 using ZB.MOM.WW.OtOpcUa.Commons.Browsing;
 using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Config;
+using ZB.MOM.WW.Secrets.Abstractions;
 
 namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Browser;
 
@@ -34,11 +35,14 @@ public sealed class GalaxyDriverBrowser : IDriverBrowser
     };
 
     private readonly ILogger<GalaxyDriverBrowser> _logger;
+    private readonly ISecretResolver _secretResolver;
 
     /// <summary>Creates a new browser. Logger defaults to <see cref="NullLogger{T}"/>.</summary>
+    /// <param name="secretResolver">Resolves the <c>secret:</c> arm of <c>Gateway.ApiKeySecretRef</c> (DI-injected).</param>
     /// <param name="logger">Optional logger; null is allowed for unit-test construction.</param>
-    public GalaxyDriverBrowser(ILogger<GalaxyDriverBrowser>? logger = null)
+    public GalaxyDriverBrowser(ISecretResolver secretResolver, ILogger<GalaxyDriverBrowser>? logger = null)
     {
+        _secretResolver = secretResolver ?? throw new ArgumentNullException(nameof(secretResolver));
         _logger = logger ?? NullLogger<GalaxyDriverBrowser>.Instance;
     }
 
@@ -68,7 +72,7 @@ public sealed class GalaxyDriverBrowser : IDriverBrowser
         if (string.IsNullOrWhiteSpace(opts.MxAccess.ClientName))
             throw new InvalidOperationException("Galaxy browser requires MxAccess.ClientName.");
 
-        var clientOpts = BuildClientOptions(opts.Gateway);
+        var clientOpts = await BuildClientOptionsAsync(opts.Gateway, cancellationToken).ConfigureAwait(false);
 
         // 30s wall-clock budget for the connect phase, linked to the caller's token so
         // an AdminUI cancel still wins early.
@@ -116,19 +120,28 @@ public sealed class GalaxyDriverBrowser : IDriverBrowser
     ///     Build the gateway client options from the form's Gateway section. Mirrors the
     ///     runtime driver's <c>GalaxyDriver.BuildClientOptions</c> field-for-field so the
     ///     gateway sees an identical option shape. The API-key reference is resolved via
-    ///     the shared <see cref="GalaxySecretRef.ResolveApiKey"/> in Driver.Galaxy.Contracts
+    ///     the shared <see cref="GalaxySecretRef.ResolveApiKeyAsync"/> in Driver.Galaxy.Contracts
     ///     (the same resolver the runtime driver uses), so browse and runtime stay in lock-step.
+    ///     The <c>secret:</c> arm is async, so the key is resolved into a local before the
+    ///     object initializer (you can't await inside one).
     /// </summary>
-    private MxGatewayClientOptions BuildClientOptions(GalaxyGatewayOptions gw) => new()
+    private async Task<MxGatewayClientOptions> BuildClientOptionsAsync(
+        GalaxyGatewayOptions gw, CancellationToken cancellationToken)
     {
-        Endpoint = new Uri(gw.Endpoint, UriKind.Absolute),
-        ApiKey = GalaxySecretRef.ResolveApiKey(gw.ApiKeySecretRef, _logger),
-        UseTls = gw.UseTls,
-        CaCertificatePath = gw.CaCertificatePath,
-        ConnectTimeout = TimeSpan.FromSeconds(gw.ConnectTimeoutSeconds),
-        DefaultCallTimeout = TimeSpan.FromSeconds(gw.DefaultCallTimeoutSeconds),
-        StreamTimeout = gw.StreamTimeoutSeconds > 0
-            ? TimeSpan.FromSeconds(gw.StreamTimeoutSeconds)
-            : null,
-    };
+        var apiKey = await GalaxySecretRef
+            .ResolveApiKeyAsync(gw.ApiKeySecretRef, _secretResolver, _logger, cancellationToken)
+            .ConfigureAwait(false);
+        return new MxGatewayClientOptions
+        {
+            Endpoint = new Uri(gw.Endpoint, UriKind.Absolute),
+            ApiKey = apiKey,
+            UseTls = gw.UseTls,
+            CaCertificatePath = gw.CaCertificatePath,
+            ConnectTimeout = TimeSpan.FromSeconds(gw.ConnectTimeoutSeconds),
+            DefaultCallTimeout = TimeSpan.FromSeconds(gw.DefaultCallTimeoutSeconds),
+            StreamTimeout = gw.StreamTimeoutSeconds > 0
+                ? TimeSpan.FromSeconds(gw.StreamTimeoutSeconds)
+                : null,
+        };
+    }
 }