test: remaining xUnit1051/1031/1030, CS8602/8604, CS0618, CS0219, CS0649, NU1510 fixes (lmxopcua#725)

Awaited deadline oracles get the runner token; sync-over-async tests made async;
nullable child models asserted via ShouldNotBeNull() return values; obsolete SDK
ctors replaced with the telemetry overloads; dead locals/fixture and the redundant
DI PackageReference removed. No suppressions.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

tests/Core/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms.Tests/ScriptedAlarmEngineTests.cs

@@ -739,7 +739,7 @@ public sealed class ScriptedAlarmEngineTests
 
             up.Push("Temp", 150);
 
-            var winner = await Task.WhenAny(ackDone.Task, Task.Delay(TimeSpan.FromSeconds(3)));
+            var winner = await Task.WhenAny(ackDone.Task, Task.Delay(TimeSpan.FromSeconds(3), TestContext.Current.CancellationToken));
             winner.ShouldBe(ackDone.Task,
                 "subscriber re-entering the engine must not deadlock against _evalGate");
             await ackDone.Task; // surface any inner exception
@@ -753,7 +753,7 @@ public sealed class ScriptedAlarmEngineTests
 
     /// <summary>Verifies that OnEvent emission occurs after the evaluation gate is released, so subscribers can re-enter the engine without deadlocking (regression for Core.ScriptedAlarms-003).</summary>
     [Fact]
-    public void OnEvent_emission_happens_outside_evalGate(/* -003 */)
+    public async Task OnEvent_emission_happens_outside_evalGate(/* -003 */)
     {
         // Direct white-box check on the gate-release ordering: AcknowledgeAsync
         // emits the Acknowledged event AFTER releasing the gate. We assert that
@@ -764,8 +764,8 @@ public sealed class ScriptedAlarmEngineTests
         var eng = Build(up, out _);
         try
         {
-            eng.LoadAsync([Alarm("HighTemp", """return (int)ctx.GetTag("Temp").Value > 100;""")],
-                TestContext.Current.CancellationToken).GetAwaiter().GetResult();
+            await eng.LoadAsync([Alarm("HighTemp", """return (int)ctx.GetTag("Temp").Value > 100;""")],
+                TestContext.Current.CancellationToken);
             // Drive to Active so Acknowledge has something to ack.
             up.Push("Temp", 150);
             // Use the same WaitForAsync that other tests use — synchronously
@@ -796,8 +796,7 @@ public sealed class ScriptedAlarmEngineTests
                 }
             };
 
-            eng.AcknowledgeAsync("HighTemp", "alice", null, CancellationToken.None)
-               .GetAwaiter().GetResult();
+            await eng.AcknowledgeAsync("HighTemp", "alice", null, CancellationToken.None);
 
             gateFreeInsideEmission.ShouldBeTrue(
                 "_evalGate must be released before OnEvent fires so subscribers " +
@@ -844,7 +843,7 @@ public sealed class ScriptedAlarmEngineTests
         // Verify Dispose does NOT complete immediately — it should block waiting
         // for the in-flight task. Without the -006 fix Dispose returns straight
         // away and the background reevaluation can outlive the engine.
-        var prematureFinish = await Task.WhenAny(disposeTask, Task.Delay(200));
+        var prematureFinish = await Task.WhenAny(disposeTask, Task.Delay(200, TestContext.Current.CancellationToken));
         prematureFinish.ShouldNotBe(disposeTask,
             "Dispose must block until in-flight background tasks complete");
 
@@ -1749,7 +1748,7 @@ public sealed class ScriptedAlarmEngineTests
         eng.InFlightCountForTest.ShouldBe(1);
 
         var disposeTask = Task.Run(() => eng.Dispose(), TestContext.Current.CancellationToken);
-        var raced = await Task.WhenAny(disposeTask, Task.Delay(300));
+        var raced = await Task.WhenAny(disposeTask, Task.Delay(300, TestContext.Current.CancellationToken));
         raced.ShouldNotBe(disposeTask, "Dispose must not return while registered background work is still running");
 
         gate.SetResult();

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting.Tests/CompiledScriptCacheTests.cs

@@ -13,11 +13,6 @@ namespace ZB.MOM.WW.OtOpcUa.Core.Scripting.Tests;
 [Trait("Category", "Unit")]
 public sealed class CompiledScriptCacheTests
 {
-    private sealed class CompileCountingGate
-    {
-        public int Count;
-    }
-
     /// <summary>Verifies that the first call to GetOrCompile compiles the script and caches the evaluator.</summary>
     [Fact]
     public void First_call_compiles_and_caches()
@@ -112,7 +107,7 @@ public sealed class CompiledScriptCacheTests
 
     /// <summary>Verifies that concurrent compiles of the same source deduplicate to a single compilation.</summary>
     [Fact]
-    public void Concurrent_compiles_of_the_same_source_deduplicate()
+    public async Task Concurrent_compiles_of_the_same_source_deduplicate()
     {
         // LazyThreadSafetyMode.ExecutionAndPublication guarantees only one compile
         // even when multiple threads race GetOrCompile against an empty cache.
@@ -122,13 +117,13 @@ public sealed class CompiledScriptCacheTests
         const string src = """return 99;""";
 
         var tasks = Enumerable.Range(0, 20)
-            .Select(_ => Task.Run(() => cache.GetOrCompile(src)))
+            .Select(_ => Task.Run(() => cache.GetOrCompile(src), TestContext.Current.CancellationToken))
             .ToArray();
-        Task.WhenAll(tasks).GetAwaiter().GetResult();
+        var evaluators = await Task.WhenAll(tasks);
 
-        var firstInstance = tasks[0].Result;
-        foreach (var t in tasks)
-            ReferenceEquals(t.Result, firstInstance).ShouldBeTrue();
+        var firstInstance = evaluators[0];
+        foreach (var e in evaluators)
+            ReferenceEquals(e, firstInstance).ShouldBeTrue();
         cache.Count.ShouldBe(1);
     }