Resolve Worker-004, -005, -006, -007, -008 code-review findings

Worker-004: post-watchdog-fault heartbeats reported a non-faulted state.
ReportWatchdogFaultIfNeededAsync now sets _state = Faulted before writing
the StaHung fault.

Worker-005 (re-triaged): the cited OnPoll site was removed by Worker-001;
the real silent-failure bug was in MxAccessStaSession.RunAlarmPollLoopAsync,
which caught only graceful-stop exceptions. A failing PollOnce now records a
WorkerFault on the event queue instead of vanishing on a non-awaited task.

Worker-006: RunAsync's finally skipped runtime disposal when shutdown timed
out, leaking the STA thread and COM object. It now always disposes
(MxAccessStaSession.Dispose is idempotent and bounded).

Worker-007 (re-triaged): replaced MxAccessComServer's Type.InvokeMember
reflection fallback with an IMxAccessServer fast path plus typed
ILMXProxyServer* casts; a non-conforming object now fails fast.

Worker-008: alarm consumer STA affinity was unenforced. MxAccessStaSession
records the alarm consumer's STA thread id and asserts every PollOnce runs
on it via a unit-testable guard.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/MxGateway.Worker.Tests/MxAccess/MxAccessComServerTests.cs

@@ -0,0 +1,138 @@
+using System;
+using System.Collections.Generic;
+using MxGateway.Worker.MxAccess;
+
+namespace MxGateway.Worker.Tests.MxAccess;
+
+/// <summary>
+/// Worker-007 regression tests for <see cref="MxAccessComServer"/>. The
+/// adapter no longer falls back to late-bound <c>Type.InvokeMember</c>
+/// reflection: a COM object must implement either the typed
+/// <c>ILMXProxyServer</c> COM interface family (production) or
+/// <see cref="IMxAccessServer"/> directly (test fakes).
+/// </summary>
+public sealed class MxAccessComServerTests
+{
+    /// <summary>
+    /// A COM object implementing <see cref="IMxAccessServer"/> is routed
+    /// through the typed interface — no reflection — preserving arguments
+    /// and return values.
+    /// </summary>
+    [Fact]
+    public void Methods_WithTypedServer_RouteThroughTypedInterface()
+    {
+        RecordingMxAccessServer typed = new(registerHandle: 77);
+        MxAccessComServer adapter = new(typed);
+
+        int serverHandle = adapter.Register("client-a");
+        adapter.Advise(serverHandle, itemHandle: 9);
+        adapter.Unregister(serverHandle);
+
+        Assert.Equal(77, serverHandle);
+        Assert.Equal("client-a", typed.RegisteredClientName);
+        Assert.Equal(new[] { "Register:client-a", "Advise:77:9", "Unregister:77" }, typed.Calls);
+    }
+
+    /// <summary>
+    /// A COM object that implements neither the typed COM interface family
+    /// nor <see cref="IMxAccessServer"/> fails fast with a clear
+    /// <see cref="InvalidOperationException"/> instead of a late-bound
+    /// reflection call.
+    /// </summary>
+    [Fact]
+    public void Methods_WithUntypedObject_ThrowInvalidOperation()
+    {
+        MxAccessComServer adapter = new(new object());
+
+        InvalidOperationException exception =
+            Assert.Throws<InvalidOperationException>(() => adapter.Register("client"));
+
+        Assert.Contains("does not implement", exception.Message, StringComparison.Ordinal);
+        Assert.Contains(nameof(IMxAccessServer), exception.Message, StringComparison.Ordinal);
+    }
+
+    /// <summary>
+    /// Exceptions thrown by the typed server propagate unchanged — no
+    /// <c>TargetInvocationException</c> wrapping (reflection is gone).
+    /// </summary>
+    [Fact]
+    public void Methods_WhenTypedServerThrows_PropagateOriginalException()
+    {
+        RecordingMxAccessServer typed = new(registerHandle: 1)
+        {
+            ThrowOnRegister = new InvalidOperationException("register failed"),
+        };
+        MxAccessComServer adapter = new(typed);
+
+        InvalidOperationException exception =
+            Assert.Throws<InvalidOperationException>(() => adapter.Register("client"));
+
+        Assert.Equal("register failed", exception.Message);
+    }
+
+    private sealed class RecordingMxAccessServer : IMxAccessServer
+    {
+        private readonly int registerHandle;
+        private readonly List<string> calls = new();
+
+        public RecordingMxAccessServer(int registerHandle)
+        {
+            this.registerHandle = registerHandle;
+        }
+
+        public string? RegisteredClientName { get; private set; }
+
+        public Exception? ThrowOnRegister { get; set; }
+
+        public IReadOnlyList<string> Calls => calls.ToArray();
+
+        public int Register(string clientName)
+        {
+            calls.Add($"Register:{clientName}");
+            RegisteredClientName = clientName;
+            if (ThrowOnRegister is not null)
+            {
+                throw ThrowOnRegister;
+            }
+
+            return registerHandle;
+        }
+
+        public void Unregister(int serverHandle)
+        {
+            calls.Add($"Unregister:{serverHandle}");
+        }
+
+        public int AddItem(int serverHandle, string itemDefinition)
+        {
+            calls.Add($"AddItem:{serverHandle}:{itemDefinition}");
+            return 0;
+        }
+
+        public int AddItem2(int serverHandle, string itemDefinition, string itemContext)
+        {
+            calls.Add($"AddItem2:{serverHandle}:{itemDefinition}:{itemContext}");
+            return 0;
+        }
+
+        public void RemoveItem(int serverHandle, int itemHandle)
+        {
+            calls.Add($"RemoveItem:{serverHandle}:{itemHandle}");
+        }
+
+        public void Advise(int serverHandle, int itemHandle)
+        {
+            calls.Add($"Advise:{serverHandle}:{itemHandle}");
+        }
+
+        public void UnAdvise(int serverHandle, int itemHandle)
+        {
+            calls.Add($"UnAdvise:{serverHandle}:{itemHandle}");
+        }
+
+        public void AdviseSupervisory(int serverHandle, int itemHandle)
+        {
+            calls.Add($"AdviseSupervisory:{serverHandle}:{itemHandle}");
+        }
+    }
+}