feat(queue): warn when the base branch has uncommitted changes

Queuing (update_task_status, batch_update_task_status) and run_task_now
now surface a non-blocking baseDirty warning (separate modified/untracked
counts) when the list's working dir has uncommitted changes at enqueue
time, since a new worktree forks from the commit tip and silently misses
them. BaseDirtyChecker caches per working dir for a few seconds so a
batch queue over many tasks in one list only shells out to git once. The
UI surfaces the same warning via the footer error strip on queue actions.

src/ClaudeDo.Ui/ViewModels/MissionControlViewModel.cs

@@ -131,7 +131,13 @@ public sealed partial class MissionControlViewModel : ViewModelBase, IDisposable
     {
         if (string.IsNullOrEmpty(taskId)) return;
         if (ConPtySessions.Any(s => s.TaskId == taskId)) return;
-        try { await _worker.SetTaskStatusAsync(taskId, ClaudeDo.Data.Models.TaskStatus.Queued); }
+        try
+        {
+            var baseDirty = await _worker.SetTaskStatusAsync(taskId, ClaudeDo.Data.Models.TaskStatus.Queued);
+            if (baseDirty is not null)
+                ErrorReported?.Invoke(Loc.T(
+                    "vm.queue.baseDirtyWarning", baseDirty.ModifiedCount, baseDirty.UntrackedCount));
+        }
         catch { /* best-effort enqueue */ }
         await RefreshQueueAsync();
     }