fix(ui): dispatch WorkerLog events to UI thread

Worker log broadcasts arrive on a SignalR thread; raising the event
directly let UI subscribers touch bindable state off-thread.

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

src/ClaudeDo.Ui/Services/WorkerClient.cs

@@ -139,7 +139,8 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
 
         _hub.On<string, WorkerLogLevel, DateTime>("WorkerLog", (message, level, timestampUtc) =>
         {
-            WorkerLogReceivedEvent?.Invoke(new WorkerLogEntry(message, level, timestampUtc));
+            Dispatcher.UIThread.Post(() =>
+                WorkerLogReceivedEvent?.Invoke(new WorkerLogEntry(message, level, timestampUtc)));
         });
 
         _hub.On<string, string>("PlanningMergeStarted", (planningTaskId, targetBranch) =>