feat(ui): highlight user chat messages + opt-in interrupt (stop) button

LogKindForegroundConverter drives the log message foreground via a local
binding (beats the dim local value), so user messages render in the accent
color instead of vanishing into the transcript. Adds a small stop (Icon.Stop)
button next to Send in both composers (SessionTerminalView + WorkConsole) wired
to InterruptInteractiveCommand → InterruptInteractiveSessionAsync. Adds
session.composer.interrupt (en/de).

src/ClaudeDo.Ui/ViewModels/Islands/TaskMonitorViewModel.cs

@@ -203,6 +203,13 @@ public sealed partial class TaskMonitorViewModel : ViewModelBase, IDisposable
             await _worker.StopInteractiveSessionAsync(_subscribedTaskId);
     }
 
+    [RelayCommand]
+    private async System.Threading.Tasks.Task InterruptInteractive()
+    {
+        if (!string.IsNullOrEmpty(_subscribedTaskId) && IsInteractiveLive)
+            await _worker.InterruptInteractiveSessionAsync(_subscribedTaskId);
+    }
+
     private void ClearPendingQuestion()
     {
         PendingQuestionId = null;