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.ControlPlane.Tests/AuditWriterActorTests.cs

@@ -21,6 +21,7 @@ public sealed class AuditWriterActorTests : ControlPlaneActorTestBase
             SourceNode: NodeId.Parse("node-a"),
             CorrelationId: CorrelationId.NewId());
 
+    /// <summary>Verifies that buffered events flush when count threshold is reached.</summary>
     [Fact]
     public void Buffered_events_flush_on_count_threshold()
     {
@@ -39,6 +40,7 @@ public sealed class AuditWriterActorTests : ControlPlaneActorTestBase
         }, duration: TimeSpan.FromSeconds(2));
     }
 
+    /// <summary>Verifies that duplicate event IDs within a batch are deduplicated in the buffer.</summary>
     [Fact]
     public void Duplicate_eventIds_within_a_batch_dedup_in_buffer()
     {
@@ -59,6 +61,7 @@ public sealed class AuditWriterActorTests : ControlPlaneActorTestBase
         db.ConfigAuditLogs.Count().ShouldBe(100, "in-buffer dedup should collapse duplicate EventIds");
     }
 
+    /// <summary>Verifies that PostStop flushes the pending buffer.</summary>
     [Fact]
     public void PostStop_flushes_pending_buffer()
     {
@@ -77,6 +80,7 @@ public sealed class AuditWriterActorTests : ControlPlaneActorTestBase
         db.ConfigAuditLogs.Count().ShouldBe(10);
     }
 
+    /// <summary>Verifies that EventId and CorrelationId are persisted to dedicated columns.</summary>
     [Fact]
     public void EventId_and_CorrelationId_are_persisted_to_dedicated_columns()
     {