feat(ui): detach a monitor into its own window

tests/ClaudeDo.Ui.Tests/ViewModels/MissionControlViewModelTests.cs

@@ -1,6 +1,7 @@
 using ClaudeDo.Data;
 using ClaudeDo.Ui.Services;
 using ClaudeDo.Ui.ViewModels;
+using ClaudeDo.Ui.ViewModels.Islands;
 using Microsoft.EntityFrameworkCore;
 using Xunit;
 
@@ -130,4 +131,25 @@ public class MissionControlViewModelTests : IDisposable
 
         Assert.Equal("t1", revealed);
     }
+
+    [Fact]
+    public void Detach_RemovesFromGrid_ThenReDockRestores()
+    {
+        var worker = new FakeWorker();
+        using var vm = BuildVm(worker);
+        TaskMonitorViewModel? detached = null;
+        Action? reDock = null;
+        vm.ShowDetached = (m, rd) => { detached = m; reDock = rd; };
+
+        worker.RaiseTaskStarted("slot-1", "t1", DateTime.UtcNow);
+        var monitor = vm.Monitors[0];
+
+        monitor.DetachCommand.Execute(null);
+        Assert.Empty(vm.Monitors);
+        Assert.Same(monitor, detached);
+
+        reDock!.Invoke();
+        Assert.Single(vm.Monitors);
+        Assert.Same(monitor, vm.Monitors[0]);
+    }
 }