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/Drivers/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.IntegrationTests/TwinCATXarFixture.cs

@@ -55,11 +55,16 @@ public sealed class TwinCATXarFixture : IAsyncLifetime
     /// <summary>TC3 PLC runtime 1. Override via <see cref="PortEnvVar"/>.</summary>
     public const int DefaultAmsPort = 851;
 
+    /// <summary>Gets the target host address.</summary>
     public string TargetHost { get; }
+    /// <summary>Gets the target AMS NetId.</summary>
     public string? TargetNetId { get; }
+    /// <summary>Gets the AMS target port.</summary>
     public int AmsPort { get; }
+    /// <summary>Gets the reason to skip tests if the fixture is unreachable.</summary>
     public string? SkipReason { get; }
 
+    /// <summary>Initializes a new instance of the TwinCATXarFixture class.</summary>
     public TwinCATXarFixture()
     {
         TargetHost  = Environment.GetEnvironmentVariable(HostEnvVar)  ?? "localhost";
@@ -82,7 +87,9 @@ public sealed class TwinCATXarFixture : IAsyncLifetime
         }
     }
 
+    /// <inheritdoc />
     public ValueTask InitializeAsync() => ValueTask.CompletedTask;
+    /// <inheritdoc />
     public ValueTask DisposeAsync() => ValueTask.CompletedTask;
 
     /// <summary><c>true</c> when the XAR runtime is reachable + the AmsNetId is set.
@@ -116,6 +123,7 @@ public sealed class TwinCATXarCollection : Xunit.ICollectionFixture<TwinCATXarFi
 /// <summary><c>[Fact]</c>-equivalent gated on <see cref="TwinCATXarFixture.IsRuntimeAvailable"/>.</summary>
 public sealed class TwinCATFactAttribute : FactAttribute
 {
+    /// <summary>Initializes a new instance of the TwinCATFactAttribute class.</summary>
     public TwinCATFactAttribute()
     {
         if (!TwinCATXarFixture.IsRuntimeAvailable())
@@ -127,6 +135,7 @@ public sealed class TwinCATFactAttribute : FactAttribute
 /// <summary><c>[Theory]</c>-equivalent with the same gate as <see cref="TwinCATFactAttribute"/>.</summary>
 public sealed class TwinCATTheoryAttribute : TheoryAttribute
 {
+    /// <summary>Initializes a new instance of the TwinCATTheoryAttribute class.</summary>
     public TwinCATTheoryAttribute()
     {
         if (!TwinCATXarFixture.IsRuntimeAvailable())