fix(host,deployment-manager,communication): repair cross-module DI regressions from batch 1-2

- DeploymentManager-008: revert IConfiguration overload (violated OptionsTests
  component-convention); Host now binds the ScadaLink:DeploymentManager section
- SiteStreamGrpcServer: make test-only int ctor internal so DI sees one public
  ctor (resolves ambiguous-constructor failure in SiteCompositionRootTests)
- Host site composition-root test config: supply Cluster:SeedNodes for the new
  ClusterOptionsValidator

tests/ScadaLink.DeploymentManager.Tests/ServiceCollectionExtensionsTests.cs

@@ -5,15 +5,32 @@ using Microsoft.Extensions.Options;
 namespace ScadaLink.DeploymentManager.Tests;
 
 /// <summary>
-/// DeploymentManager-008: DeploymentManagerOptions must be bound to the
-/// "ScadaLink:DeploymentManager" configuration section, consistent with the
-/// Options-pattern convention used by the other components.
+/// DeploymentManager-008: DeploymentManagerOptions must be resolvable via the
+/// Options pattern and bindable to the "ScadaLink:DeploymentManager"
+/// configuration section. The component itself does not depend on
+/// IConfiguration (enforced by Host's OptionsTests) — the Host binds the
+/// section; AddDeploymentManager only guarantees IOptions resolvability.
 /// </summary>
 public class ServiceCollectionExtensionsTests
 {
     [Fact]
-    public void AddDeploymentManager_WithConfiguration_BindsDeploymentManagerOptions()
+    public void AddDeploymentManager_RegistersResolvableOptions_WithDefaults()
     {
+        var services = new ServiceCollection();
+        services.AddDeploymentManager();
+
+        using var provider = services.BuildServiceProvider();
+        var options = provider.GetRequiredService<IOptions<DeploymentManagerOptions>>().Value;
+
+        // No section bound -> the option-class defaults are retained.
+        Assert.Equal(TimeSpan.FromSeconds(5), options.OperationLockTimeout);
+    }
+
+    [Fact]
+    public void AddDeploymentManager_OptionsBindToConfigurationSection_AsTheHostWires()
+    {
+        // Mirrors the Host wiring: the Host calls Configure<DeploymentManagerOptions>
+        // against OptionsSection, then AddDeploymentManager().
         var configuration = new ConfigurationBuilder()
             .AddInMemoryCollection(new Dictionary<string, string?>
             {
@@ -23,7 +40,9 @@ public class ServiceCollectionExtensionsTests
             .Build();
 
         var services = new ServiceCollection();
-        services.AddDeploymentManager(configuration);
+        services.Configure<DeploymentManagerOptions>(
+            configuration.GetSection(ServiceCollectionExtensions.OptionsSection));
+        services.AddDeploymentManager();
 
         using var provider = services.BuildServiceProvider();
         var options = provider.GetRequiredService<IOptions<DeploymentManagerOptions>>().Value;
@@ -33,17 +52,8 @@ public class ServiceCollectionExtensionsTests
     }
 
     [Fact]
-    public void AddDeploymentManager_WithConfiguration_MissingSection_UsesDefaults()
+    public void OptionsSection_MatchesTheConventionalComponentSectionPath()
     {
-        var configuration = new ConfigurationBuilder().Build();
-
-        var services = new ServiceCollection();
-        services.AddDeploymentManager(configuration);
-
-        using var provider = services.BuildServiceProvider();
-        var options = provider.GetRequiredService<IOptions<DeploymentManagerOptions>>().Value;
-
-        // No section present -> the option-class defaults are retained.
-        Assert.Equal(TimeSpan.FromSeconds(5), options.OperationLockTimeout);
+        Assert.Equal("ScadaLink:DeploymentManager", ServiceCollectionExtensions.OptionsSection);
     }
 }