refactor(driver-pages): address Phase 6/8 deep-review findings

- Topic-name drift fix: DriverHealthChanged.TopicName and
  DriverControlTopic.Name now live on the message contracts in
  Commons. AkkaDriverHealthPublisher, DriverStatusSignalRBridge,
  DriverHostActor, and AdminOperationsActor all delegate to the
  single constant so a rename can't silently desynchronise
  publisher and subscriber.
- DriverStatusPanel._opResultClearTimer switched from
  System.Timers.Timer to System.Threading.Timer + awaited
  DisposeAsync. Prevents an in-flight 8s clear-callback from
  invoking StateHasChanged on a component whose hub has already
  been released.
- PublishHealthSnapshot deduplicates against the last published
  (state, lastSuccess, lastError, errorCount) fingerprint. The
  30s heartbeat no longer floods the SignalR layer with identical
  Healthy snapshots — newly-joined clients still warm up via the
  snapshot store on JoinDriver.

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverInstanceActor.cs

@@ -434,13 +434,22 @@ public sealed class DriverInstanceActor : ReceiveActor, IWithTimers
     ///     Polls <see cref="IDriver.GetHealth"/> and forwards the snapshot to the health publisher.
     ///     Called on every observable state change and by the periodic <see cref="HealthPollTick"/>
     ///     so the AdminUI snapshot store is warmed up for newly-joined SignalR clients.
+    ///     Deduplicates: if the resulting (state, lastSuccess, lastError, errorCount) tuple matches
+    ///     the last publish, this call is a no-op. Stops flood-publishing identical Healthy snapshots
+    ///     every 30s when nothing has changed. Newly-joined SignalR clients still get the current
+    ///     snapshot via <c>DriverStatusHub.JoinDriver</c> which reads the store directly.
     /// </summary>
     private void PublishHealthSnapshot()
     {
         try
         {
             var health = _driver.GetHealth();
-            _healthPublisher.Publish(_clusterId, _driverInstanceId, health, ErrorCount5Min());
+            var errorCount = ErrorCount5Min();
+            var fingerprint = (health.State, health.LastSuccessfulRead, health.LastError, errorCount);
+            if (_lastPublishedFingerprint is { } prev && prev.Equals(fingerprint))
+                return;
+            _lastPublishedFingerprint = fingerprint;
+            _healthPublisher.Publish(_clusterId, _driverInstanceId, health, errorCount);
         }
         catch (Exception ex)
         {
@@ -448,6 +457,9 @@ public sealed class DriverInstanceActor : ReceiveActor, IWithTimers
         }
     }
 
+    /// <summary>Fingerprint of the last <see cref="PublishHealthSnapshot"/> call; null until first publish.</summary>
+    private (DriverState State, DateTime? LastSuccess, string? LastError, int ErrorCount)? _lastPublishedFingerprint;
+
     /// <inheritdoc />
     protected override void PostStop()
     {