docs(tests): fix CommentChecker findings across tests/ — 13,392 → 0 (repo-wide scan clean)

Comment/XML-doc changes only:
- add summaries to ~10k test methods, fixtures, fakes and helpers
  (+ <param> on theories, <returns> on async Task methods,
  <inheritdoc/> on interface implementations the checker can resolve)
- strip ~2.6k project-tracking references (WP*, P*-*, row-NN, Task N,
  #NN, Component-0NN) from comments, keeping the explanatory text;
  reword false positives in comments only
- real docs on fakes implementing BCL/library interfaces
  (IDisposable, ILogger, IOptionsMonitor, IAsyncLifetime)
- reword the last 5 src/ false positives (CWE-1236, failures-1,
  year-0001, M365)

Only non-comment edits: four one-line nested classes split across lines
so members can carry docs. Build 0 errors / 0 warnings.

tests/ZB.MOM.WW.ScadaBridge.Host.Tests/SingletonRegistrarTests.cs

@@ -9,9 +9,12 @@ public class SingletonRegistrarTests
 {
     private sealed class EchoActor : ReceiveActor
     {
+        /// <summary>Creates an actor that echoes every message back to its sender.</summary>
         public EchoActor() => ReceiveAny(m => Sender.Tell(m));
     }
 
+    /// <summary>Verifies that starting a singleton creates the manager and proxy with canonical names and a drain task.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Start_CreatesManagerAndProxy_WithCanonicalNames_AndDrainTask()
     {
@@ -36,10 +39,12 @@ public class SingletonRegistrarTests
         Assert.True(handle.Manager.IsNobody() || system.WhenTerminated.IsCompleted);
     }
 
+    /// <summary>Verifies that starting a singleton with a role scope creates a role-scoped singleton that answers requests.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Start_WithRoleScope_CreatesRoleScopedSingleton_ThatAnswers()
     {
-        // Round-2 N5: role scoping is what kept the two SITE singletons
+        // Role scoping is what kept the two SITE singletons
         // (deployment-manager, event-log-handler) hand-rolled and drain-less.
         using var system = CreateSingleNodeClusterSystem(); // roles = ["Central"]
         var handle = SingletonRegistrar.Start(