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/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/DeferredAddressSpaceSinkTests.cs

@@ -7,6 +7,7 @@ namespace ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests;
 
 public sealed class DeferredAddressSpaceSinkTests
 {
+    /// <summary>Verifies that the default inner is a null sink so calls before SetSink are safe.</summary>
     [Fact]
     public void Default_inner_is_null_sink_so_calls_before_SetSink_are_safe()
     {
@@ -18,6 +19,7 @@ public sealed class DeferredAddressSpaceSinkTests
         deferred.RebuildAddressSpace();
     }
 
+    /// <summary>Verifies that calls after SetSink are forwarded to the inner sink.</summary>
     [Fact]
     public void Calls_after_SetSink_are_forwarded_to_the_inner()
     {
@@ -32,6 +34,7 @@ public sealed class DeferredAddressSpaceSinkTests
         inner.Calls.ShouldBe(new[] { "WV:x", "WA:a-1", "RB" });
     }
 
+    /// <summary>Verifies that setting sink to null reverts to null sink.</summary>
     [Fact]
     public void SetSink_to_null_reverts_to_null_sink()
     {
@@ -46,6 +49,7 @@ public sealed class DeferredAddressSpaceSinkTests
         inner.Calls.Count.ShouldBe(1);
     }
 
+    /// <summary>Verifies that sink can be swapped between implementations.</summary>
     [Fact]
     public void SetSink_can_swap_between_implementations()
     {
@@ -65,15 +69,21 @@ public sealed class DeferredAddressSpaceSinkTests
 
     private sealed class RecordingSink : IOpcUaAddressSpaceSink
     {
+        /// <summary>Gets the queue of recorded calls.</summary>
         public ConcurrentQueue<string> CallQueue { get; } = new();
+        /// <summary>Gets the list of recorded calls.</summary>
         public List<string> Calls => CallQueue.ToList();
 
+        /// <inheritdoc />
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc)
             => CallQueue.Enqueue($"WV:{nodeId}");
+        /// <inheritdoc />
         public void WriteAlarmState(string alarmNodeId, bool active, bool acknowledged, DateTime sourceTimestampUtc)
             => CallQueue.Enqueue($"WA:{alarmNodeId}");
+        /// <inheritdoc />
         public void EnsureFolder(string folderNodeId, string? parentNodeId, string displayName)
             => CallQueue.Enqueue($"EF:{folderNodeId}");
+        /// <inheritdoc />
         public void RebuildAddressSpace() => CallQueue.Enqueue("RB");
     }
 }