Add XML documentation across gateway, worker, and .NET client

src/MxGateway.Worker/MxAccess/MxAccessCreationException.cs

@@ -3,8 +3,11 @@ using System.Runtime.InteropServices;
 
 namespace MxGateway.Worker.MxAccess;
 
+/// <summary>Thrown when the worker fails to instantiate the MXAccess COM object.</summary>
 public sealed class MxAccessCreationException : Exception
 {
+    /// <summary>Initializes a new instance with diagnostic info from the inner exception.</summary>
+    /// <param name="innerException">The exception that caused the creation failure.</param>
     public MxAccessCreationException(Exception innerException)
         : base(
             $"Failed to create MXAccess COM object {MxAccessInteropInfo.ComClassName} ({MxAccessInteropInfo.ProgId}).",
@@ -16,14 +19,21 @@ public sealed class MxAccessCreationException : Exception
         HResult = innerException.HResult;
     }
 
+    /// <summary>The ProgID that was attempted during COM instantiation.</summary>
     public string AttemptedProgId { get; }
 
+    /// <summary>The CLSID that was attempted during COM instantiation.</summary>
     public string AttemptedClsid { get; }
 
+    /// <summary>The COM class name that was attempted during instantiation.</summary>
     public string AttemptedComClassName { get; }
 
+    /// <summary>The captured HResult from the instantiation failure, or null if zero.</summary>
     public int? CapturedHResult => HResult == 0 ? null : HResult;
 
+    /// <summary>Wraps an exception in MxAccessCreationException if it is not already.</summary>
+    /// <param name="exception">The exception to wrap.</param>
+    /// <returns>An MxAccessCreationException wrapping the input exception.</returns>
     public static MxAccessCreationException From(Exception exception)
     {
         return exception is MxAccessCreationException creationException
@@ -31,6 +41,9 @@ public sealed class MxAccessCreationException : Exception
             : new MxAccessCreationException(exception);
     }
 
+    /// <summary>Extracts the HResult from an exception, handling MXAccess and COM exceptions specially.</summary>
+    /// <param name="exception">The exception to extract the HResult from.</param>
+    /// <returns>The HResult value, or null if zero.</returns>
     public static int? ExtractHResult(Exception exception)
     {
         if (exception is MxAccessCreationException creationException)