worker(alarms): UnAdvise only advised handles in LmxSubtagAlarmSource teardown

B3: track advised handles separately from added handles so Dispose only UnAdvises
items that were actually advised — a write-only subtag (e.g. ack-comment added by
Write, never advised) is removed but not unadvised. Add Dispose tests covering the
advised/write-only split, full removal, single Unregister, and double-dispose
idempotency.

src/ZB.MOM.WW.MxGateway.Worker/MxAccess/LmxSubtagAlarmSource.cs

@@ -46,6 +46,12 @@ public sealed class LmxSubtagAlarmSource : ISubtagAlarmSource
     private readonly Dictionary<int, string> addressesByItemHandle =
         new Dictionary<int, string>();
 
+    // Handles that were actually Advise()d, tracked separately from the added
+    // set so Dispose only UnAdvises advised items. Write() can AddItem a
+    // write-only subtag (e.g. an ack-comment that was never advised); calling
+    // UnAdvise on such a handle would be an unbalanced teardown.
+    private readonly HashSet<int> advisedItemHandles = new HashSet<int>();
+
     private object? mxAccessComObject;
     private IMxAccessServer? server;
     private LMXProxyServerClass? comEventSource;
@@ -134,6 +140,7 @@ public sealed class LmxSubtagAlarmSource : ISubtagAlarmSource
             mxServer.Advise(serverHandle, itemHandle);
             itemHandlesByAddress[itemAddress!] = itemHandle;
             addressesByItemHandle[itemHandle] = itemAddress!;
+            advisedItemHandles.Add(itemHandle);
         }
     }
 
@@ -225,7 +232,13 @@ public sealed class LmxSubtagAlarmSource : ISubtagAlarmSource
         {
             foreach (KeyValuePair<int, string> entry in addressesByItemHandle)
             {
-                try { mxServer.UnAdvise(serverHandle, entry.Key); } catch { /* swallow — best effort */ }
+                // Only UnAdvise handles that were actually advised; a write-only
+                // item (added by Write but never Advise'd) was never advised.
+                if (advisedItemHandles.Contains(entry.Key))
+                {
+                    try { mxServer.UnAdvise(serverHandle, entry.Key); } catch { /* swallow — best effort */ }
+                }
+
                 try { mxServer.RemoveItem(serverHandle, entry.Key); } catch { /* swallow — best effort */ }
             }
 
@@ -234,6 +247,7 @@ public sealed class LmxSubtagAlarmSource : ISubtagAlarmSource
 
         itemHandlesByAddress.Clear();
         addressesByItemHandle.Clear();
+        advisedItemHandles.Clear();
 
         object? comToRelease = mxAccessComObject;
         mxAccessComObject = null;