docs: complete XML doc comments via fixdocs (2757 to 131 findings)

Add missing <returns>/<param>/<summary>/<typeparam> tags and clean up
misused inheritdoc across 481 files so the documented API surface is
complete. Documentation-only (zero code lines changed). The 131 remaining
findings are inheritdoc-style warnings deliberately left to preserve
hand-written implementation rationale (plan-decision notes, race-condition
explanations).

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

@@ -77,6 +77,7 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
 
     /// <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>
+    /// <returns>A task that resolves to the started two-node cluster harness.</returns>
     public static async Task<TwoNodeClusterHarness> StartAsync(TimeSpan? formationTimeout = null)
     {
         var harness = new TwoNodeClusterHarness();
@@ -108,6 +109,7 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
     /// a couple of seconds. Use this for failover scenarios; call <see cref="RestartNodeBAsync"/>
     /// to bring it back on the same Akka port.
     /// </summary>
+    /// <returns>A task that represents the asynchronous stop operation.</returns>
     public async Task StopNodeBAsync()
     {
         if (NodeB is null) return;
@@ -120,6 +122,7 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
     /// 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>
+    /// <returns>A task that represents the asynchronous restart operation.</returns>
     public async Task RestartNodeBAsync(TimeSpan? formationTimeout = null)
     {
         NodeB = await BuildNodeAsync(this, NodeRole.Joiner);
@@ -136,6 +139,7 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
     /// </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>
+    /// <returns>A task that represents the asynchronous wait operation.</returns>
     public async Task WaitForClusterSizeAsync(int expectedUpMembers, TimeSpan timeout)
     {
         var deadline = DateTime.UtcNow + timeout;
@@ -280,6 +284,7 @@ public sealed class TwoNodeClusterHarness : IAsyncDisposable
     }
 
     /// <summary>Asynchronously disposes both nodes and cleans up the SQL database if used.</summary>
+    /// <returns>A value task that represents the asynchronous dispose operation.</returns>
     public async ValueTask DisposeAsync()
     {
         if (NodeB is not null) await NodeB.DisposeAsync();
@@ -303,11 +308,7 @@ 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>
+        /// <inheritdoc />
         public Task<LdapAuthResult> AuthenticateAsync(string username, string password, CancellationToken ct = default)
             => Task.FromResult(new LdapAuthResult(
                 Success: password == "valid-password",