docs: complete XML doc comments via fixdocs (2757 to 131 findings)

Add missing <returns>/<param>/<summary>/<typeparam> tags and clean up
misused inheritdoc across 481 files so the documented API surface is
complete. Documentation-only (zero code lines changed). The 131 remaining
findings are inheritdoc-style warnings deliberately left to preserve
hand-written implementation rationale (plan-decision notes, race-condition
explanations).

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Health/HealthProbeActorTests.cs

@@ -16,6 +16,7 @@ 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>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task DbHealthProbeActor_returns_reachable_against_in_memory_db()
     {
@@ -92,6 +93,7 @@ public sealed class HealthProbeActorTests : RuntimeActorTestBase
     }
 
     /// <summary>Verifies that the historian adapter actor returns sink status via GetStatus.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task HistorianAdapterActor_returns_sink_status_via_GetStatus()
     {
@@ -115,16 +117,14 @@ public sealed class HealthProbeActorTests : RuntimeActorTestBase
         /// <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>
+        /// <inheritdoc />
         public Task EnqueueAsync(AlarmHistorianEvent evt, CancellationToken cancellationToken)
         {
             Enqueued.Add(evt);
             return Task.CompletedTask;
         }
 
-        /// <summary>Gets the current status of the historian sink.</summary>
+        /// <inheritdoc />
         public HistorianSinkStatus GetStatus() => new(
             QueueDepth: Enqueued.Count,
             DeadLetterDepth: 0,