docs: backfill XML documentation across 756 files

Adds <summary>, <param>, <typeparam>, and <inheritdoc/> tags to public
members surfaced by commentchecker — resolves 5,847 of 5,869 issues
(99.6%) across three /fixdocs passes.

tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/TwoNodeClusterHarness.cs

@@ -48,26 +48,35 @@ namespace ZB.MOM.WW.OtOpcUa.Host.IntegrationTests;
 public sealed class TwoNodeClusterHarness : IAsyncDisposable
 {
     public const string TestRoles = "admin,driver";
+    /// <summary>Gets the shared database name for both cluster nodes.</summary>
     public string SharedDbName { get; } = $"two-node-cluster-{Guid.NewGuid():N}";
 
+    /// <summary>Gets the harness mode configuration from environment variables.</summary>
     public HarnessMode Mode { get; } = HarnessMode.FromEnvironment();
     private string? _sqlDbName;
     private string? _sqlConnString;
 
+    /// <summary>Gets the first web application node.</summary>
     public WebApplication NodeA { get; private set; } = null!;
+    /// <summary>Gets the second web application node.</summary>
     public WebApplication NodeB { get; private set; } = null!;
 
+    /// <summary>Gets the Akka port allocated for node A.</summary>
     public int NodeAAkkaPort { get; private set; }
+    /// <summary>Gets the Akka port allocated for node B.</summary>
     public int NodeBAkkaPort { get; private set; }
 
     // Both nodes bind to 127.0.0.1 — ClusterRoleInfo + ConfigPublishCoordinator encode
     // host:port into NodeId so the cluster membership stays distinct on different ports.
     public const string LoopbackHost = "127.0.0.1";
 
+    /// <summary>Gets the Akka ActorSystem for node A.</summary>
     public ActorSystem NodeASystem => NodeA.Services.GetRequiredService<ActorSystem>();
+    /// <summary>Gets the Akka ActorSystem for node B.</summary>
     public ActorSystem NodeBSystem => NodeB.Services.GetRequiredService<ActorSystem>();
 
     /// <summary>Boots both nodes and waits up to <paramref name="formationTimeout"/> for cluster convergence.</summary>
+    /// <param name="formationTimeout">Maximum time to wait for cluster formation; defaults to 20 seconds if not provided.</param>
     public static async Task<TwoNodeClusterHarness> StartAsync(TimeSpan? formationTimeout = null)
     {
         var harness = new TwoNodeClusterHarness();
@@ -110,6 +119,7 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
     /// Rebuilds node B on the same Akka port + same ConfigDb and waits for the cluster
     /// to re-converge to 2 Up members. Use after <see cref="StopNodeBAsync"/> to test rejoin.
     /// </summary>
+    /// <param name="formationTimeout">The maximum time to wait for cluster formation; defaults to 20 seconds.</param>
     public async Task RestartNodeBAsync(TimeSpan? formationTimeout = null)
     {
         NodeB = await BuildNodeAsync(this, NodeRole.Joiner);
@@ -124,6 +134,8 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
     /// Waits for node A's cluster view to reach <paramref name="expectedUpMembers"/> members in
     /// <see cref="MemberStatus.Up"/>. Used for asserting shrink-after-stop or grow-after-restart.
     /// </summary>
+    /// <param name="expectedUpMembers">The expected number of Up members in the cluster.</param>
+    /// <param name="timeout">The maximum time to wait for the expected cluster size.</param>
     public async Task WaitForClusterSizeAsync(int expectedUpMembers, TimeSpan timeout)
     {
         var deadline = DateTime.UtcNow + timeout;
@@ -265,6 +277,7 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
         return port;
     }
 
+    /// <summary>Asynchronously disposes both nodes and cleans up the SQL database if used.</summary>
     public async ValueTask DisposeAsync()
     {
         if (NodeB is not null) await NodeB.DisposeAsync();
@@ -279,6 +292,8 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
     /// <summary>Captures the env-var driven harness mode at construction time.</summary>
     public sealed record HarnessMode(bool UseSqlServer, bool UseRealLdap)
     {
+        /// <summary>Creates a HarnessMode from environment variable settings.</summary>
+        /// <returns>A HarnessMode configured from OTOPCUA_HARNESS_USE_SQL and OTOPCUA_HARNESS_USE_LDAP environment variables.</returns>
         public static HarnessMode FromEnvironment() => new(
             UseSqlServer: Environment.GetEnvironmentVariable("OTOPCUA_HARNESS_USE_SQL") == "1",
             UseRealLdap: Environment.GetEnvironmentVariable("OTOPCUA_HARNESS_USE_LDAP") == "1");
@@ -286,6 +301,11 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
 
     private sealed class StubLdapAuthService : ILdapAuthService
     {
+        /// <summary>Asynchronously authenticates a user with the stub LDAP service.</summary>
+        /// <param name="username">The username to authenticate.</param>
+        /// <param name="password">The password to authenticate against.</param>
+        /// <param name="ct">The cancellation token.</param>
+        /// <returns>A task that returns the LDAP authentication result.</returns>
         public Task<LdapAuthResult> AuthenticateAsync(string username, string password, CancellationToken ct = default)
             => Task.FromResult(new LdapAuthResult(
                 Success: password == "valid-password",