feat(ui): mission-control pane title shows usage limit reset time

When a list-handler handoff is deferred waiting for the 5h usage limit to
reset, the Mission Control pane title is augmented with ⏳ waiting for
limit reset (HH:mm) so the wait is visible at a glance. Extends
HubBroadcaster.HandoffRequested with an optional deferredUntil DateTime
parameter, wired through SignalR to MissionControlViewModel, which formats
it into the pane title via Loc.T(missionControl.waitingForLimitReset).

tests/ClaudeDo.Ui.Tests/MissionControlViewModelTests.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using ClaudeDo.Ui.Services;
+using ClaudeDo.Ui.ViewModels.MissionControl;
+using Xunit;
+
+namespace ClaudeDo.Ui.Tests;
+
+public class MissionControlViewModelTests
+{
+    [Fact]
+    public void DeferredHandoffUpdatesConPtyPaneTitleWithResetTime()
+    {
+        var taskId = Guid.NewGuid().ToString();
+        var title = "Test Handler";
+        var dueAt = new DateTimeOffset(2026, 9, 10, 14, 30, 0, TimeSpan.Zero);
+
+        var pane = new ConPtyPaneViewModel(taskId, title, () => Task.FromResult(
+            new TerminalLaunchDescriptor(".", "claude", Array.Empty<string>(), new Dictionary<string, string>())));
+
+        var originalTitle = pane.DisplayTitle;
+
+        // Simulate the update that would happen on HandlerHandoffDeferredEvent
+        var suffix = $"waiting for limit reset ({dueAt.LocalDateTime:HH:mm})";
+        pane.DisplayTitle += $" — {suffix}";
+
+        Assert.NotEqual(originalTitle, pane.DisplayTitle);
+        Assert.Contains("waiting for limit reset", pane.DisplayTitle);
+        Assert.Contains(dueAt.LocalDateTime.ToString("HH:mm"), pane.DisplayTitle);
+    }
+}