feat(lmxproxy): phase 7 — integration tests, deployment to windev, v1 cutover

- Replaced STA dispatch thread with Task.Run pattern for COM interop
- Fixed TypedValue oneof tracking with property-level _setCase field
- Added x-api-key DelegatingHandler for gRPC metadata authentication
- Fixed CheckApiKey RPC to validate request body key (not header)
- Integration tests: 15/17 pass (reads, subscribes, API keys, connections)
- 2 write tests pending (OnWriteComplete callback timing issue)
- v2 service deployed on windev port 50100

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lmxproxy/src/ZB.MOM.WW.LmxProxy.Host/MxAccess/MxAccessClient.cs

@@ -10,13 +10,13 @@ namespace ZB.MOM.WW.LmxProxy.Host.MxAccess
 {
     /// <summary>
     ///     Wraps the ArchestrA MXAccess COM API. All COM operations
-    ///     execute on a dedicated STA thread via <see cref="StaDispatchThread"/>.
+    ///     execute via Task.Run (thread pool / MTA), relying on COM
+    ///     marshaling to handle cross-apartment calls.
     /// </summary>
     public sealed partial class MxAccessClient : IScadaClient
     {
         private static readonly ILogger Log = Serilog.Log.ForContext<MxAccessClient>();
 
-        private readonly StaDispatchThread _staThread;
         private readonly object _lock = new object();
         private readonly int _maxConcurrentOperations;
         private readonly int _readTimeoutMs;
@@ -29,7 +29,7 @@ namespace ZB.MOM.WW.LmxProxy.Host.MxAccess
         private readonly SemaphoreSlim _readSemaphore;
         private readonly SemaphoreSlim _writeSemaphore;
 
-        // COM objects — only accessed on STA thread
+        // COM objects
         private LMXProxyServer? _lmxProxy;
         private int _connectionHandle;
 
@@ -45,6 +45,17 @@ namespace ZB.MOM.WW.LmxProxy.Host.MxAccess
         private readonly Dictionary<string, Action<string, Vtq>> _storedSubscriptions
             = new Dictionary<string, Action<string, Vtq>>(StringComparer.OrdinalIgnoreCase);
 
+        // Handle-to-address mapping for resolving COM callbacks
+        private readonly Dictionary<int, string> _handleToAddress = new Dictionary<int, string>();
+
+        // Address-to-handle mapping for unsubscribe by address
+        private readonly Dictionary<string, int> _addressToHandle
+            = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase);
+
+        // Pending write operations tracked by item handle
+        private readonly Dictionary<int, TaskCompletionSource<bool>> _pendingWrites
+            = new Dictionary<int, TaskCompletionSource<bool>>();
+
         public MxAccessClient(
             int maxConcurrentOperations = 10,
             int readTimeoutSeconds = 5,
@@ -64,7 +75,6 @@ namespace ZB.MOM.WW.LmxProxy.Host.MxAccess
 
             _readSemaphore = new SemaphoreSlim(maxConcurrentOperations, maxConcurrentOperations);
             _writeSemaphore = new SemaphoreSlim(maxConcurrentOperations, maxConcurrentOperations);
-            _staThread = new StaDispatchThread();
         }
 
         public bool IsConnected
@@ -123,7 +133,6 @@ namespace ZB.MOM.WW.LmxProxy.Host.MxAccess
 
             _readSemaphore.Dispose();
             _writeSemaphore.Dispose();
-            _staThread.Dispose();
             _reconnectCts?.Dispose();
         }
     }