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.UI.Tests/Fakes/FakeSettingsService.cs

@@ -4,17 +4,24 @@ namespace ZB.MOM.WW.OtOpcUa.Client.UI.Tests.Fakes;
 
 public sealed class FakeSettingsService : ISettingsService
 {
+    /// <summary>Gets or sets the settings held by this fake service.</summary>
     public UserSettings Settings { get; set; } = new();
+    /// <summary>Gets the number of times Load has been called.</summary>
     public int LoadCallCount { get; private set; }
+    /// <summary>Gets the number of times Save has been called.</summary>
     public int SaveCallCount { get; private set; }
+    /// <summary>Gets the last settings that were saved.</summary>
     public UserSettings? LastSaved { get; private set; }
 
+    /// <summary>Loads and returns the current settings.</summary>
     public UserSettings Load()
     {
         LoadCallCount++;
         return Settings;
     }
 
+    /// <summary>Saves the specified settings.</summary>
+    /// <param name="settings">The settings to save.</param>
     public void Save(UserSettings settings)
     {
         SaveCallCount++;