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.Runtime.Tests/Health/HealthProbeActorTests.cs

@@ -15,6 +15,7 @@ namespace ZB.MOM.WW.OtOpcUa.Runtime.Tests.Health;
 
 public sealed class HealthProbeActorTests : RuntimeActorTestBase
 {
+    /// <summary>Verifies that the DB health probe actor returns reachable status against an in-memory database.</summary>
     [Fact]
     public async Task DbHealthProbeActor_returns_reachable_against_in_memory_db()
     {
@@ -28,6 +29,7 @@ public sealed class HealthProbeActorTests : RuntimeActorTestBase
         status.LastError.ShouldBeNull();
     }
 
+    /// <summary>Verifies that the peer OPC UA probe actor reports Ok true against a live listener.</summary>
     [Fact]
     public void PeerOpcUaProbeActor_reports_Ok_true_against_a_live_listener()
     {
@@ -47,6 +49,7 @@ public sealed class HealthProbeActorTests : RuntimeActorTestBase
             TimeSpan.FromSeconds(3));
     }
 
+    /// <summary>Verifies that the peer OPC UA probe actor reports Ok false against an unreachable endpoint.</summary>
     [Fact]
     public void PeerOpcUaProbeActor_reports_Ok_false_against_an_unreachable_endpoint()
     {
@@ -63,6 +66,7 @@ public sealed class HealthProbeActorTests : RuntimeActorTestBase
             TimeSpan.FromSeconds(3));
     }
 
+    /// <summary>Verifies that the historian adapter actor forwards events to the injected sink.</summary>
     [Fact]
     public void HistorianAdapterActor_forwards_events_to_injected_sink()
     {
@@ -87,6 +91,7 @@ public sealed class HealthProbeActorTests : RuntimeActorTestBase
             new[] { "alm-0", "alm-1", "alm-2", "alm-3", "alm-4" });
     }
 
+    /// <summary>Verifies that the historian adapter actor returns sink status via GetStatus.</summary>
     [Fact]
     public async Task HistorianAdapterActor_returns_sink_status_via_GetStatus()
     {
@@ -107,14 +112,19 @@ public sealed class HealthProbeActorTests : RuntimeActorTestBase
 
     private sealed class RecordingSink : IAlarmHistorianSink
     {
+        /// <summary>Gets the list of enqueued alarm historian events.</summary>
         public ConcurrentBag<AlarmHistorianEvent> Enqueued { get; } = [];
 
+        /// <summary>Enqueues an alarm historian event.</summary>
+        /// <param name="evt">The event to enqueue.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
         public Task EnqueueAsync(AlarmHistorianEvent evt, CancellationToken cancellationToken)
         {
             Enqueued.Add(evt);
             return Task.CompletedTask;
         }
 
+        /// <summary>Gets the current status of the historian sink.</summary>
         public HistorianSinkStatus GetStatus() => new(
             QueueDepth: Enqueued.Count,
             DeadLetterDepth: 0,