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/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Fakes/FakeEndpointDiscovery.cs

@@ -5,10 +5,18 @@ namespace ZB.MOM.WW.OtOpcUa.Client.Shared.Tests.Fakes;
 
 internal sealed class FakeEndpointDiscovery : IEndpointDiscovery
 {
+    /// <summary>Gets or sets a value indicating whether SelectEndpoint should throw an exception.</summary>
     public bool ThrowOnSelect { get; set; }
+    /// <summary>Gets the number of times SelectEndpoint has been called.</summary>
     public int SelectCallCount { get; private set; }
+    /// <summary>Gets the last endpoint URL passed to SelectEndpoint.</summary>
     public string? LastEndpointUrl { get; private set; }
 
+    /// <summary>Selects an endpoint for the given configuration and URL, optionally throwing an exception.</summary>
+    /// <param name="config">The application configuration.</param>
+    /// <param name="endpointUrl">The endpoint URL to select.</param>
+    /// <param name="requestedMode">The requested security mode.</param>
+    /// <returns>The selected endpoint description.</returns>
     public EndpointDescription SelectEndpoint(ApplicationConfiguration config, string endpointUrl,
         MessageSecurityMode requestedMode)
     {