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.OpcUaClient.IntegrationTests/OpcPlcFixture.cs

@@ -41,10 +41,16 @@ public sealed class OpcPlcFixture : IAsyncDisposable
 
     /// <summary>Full <c>opc.tcp://host:port</c> URL the driver session should connect to.</summary>
     public string EndpointUrl { get; }
+    /// <summary>Gets the host name of the OPC UA simulator.</summary>
     public string Host { get; }
+    /// <summary>Gets the port number of the OPC UA simulator.</summary>
     public int Port { get; }
+    /// <summary>Gets a skip reason if the simulator is unreachable; otherwise null.</summary>
     public string? SkipReason { get; }
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="OpcPlcFixture"/> class and probes the simulator.
+    /// </summary>
     public OpcPlcFixture()
     {
         EndpointUrl = Environment.GetEnvironmentVariable(EndpointEnvVar) ?? DefaultEndpoint;
@@ -91,6 +97,9 @@ public sealed class OpcPlcFixture : IAsyncDisposable
         return int.TryParse(body[(colon + 1)..], out var p) ? (host, p) : (host, 4840);
     }
 
+    /// <summary>
+    /// Disposes the fixture resources (currently a no-op).
+    /// </summary>
     public ValueTask DisposeAsync() => ValueTask.CompletedTask;
 }