fix(ui): refresh the run session id live, close the stale handoff pane

A task selected before its run started kept LatestRunSessionId null, so the
roadblock reply box and Continue stayed dead until it was re-selected.

The handoff left the Phase 1-2 tile open so its last message could be read, but
its process is gone by then and the terminal renders empty -- a dead
placeholder. It is closed on handoff now.

Also drops the WARN flood from worktree cleanup (already-unregistered worktree
and already-deleted branch are normal outcomes, not failures) and replaces the
fixed sleep in UsageGate_TransitionLogging_FiresOncePerChange with the polling
helper that already sits three lines below it in the same file.

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

@@ -366,6 +366,10 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             if (Task?.Id != taskId) return;
             _ = RefreshWorktreeAsync(taskId);
             _ = RefreshChildOutcomeAsync(taskId);
+            // The run only gets a session id once it has started, so a task that was already
+            // selected while it ran still holds the null from selection time. Without this the
+            // roadblock reply box and Continue stay dead until the task is re-selected.
+            _ = RefreshLatestRunSessionIdAsync(taskId);
         };
         _worker.TaskFinishedEvent += _workerTaskFinishedHandler;
 
@@ -801,6 +805,18 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
     // Refreshes the bound row itself (status, planning phase, worktree/branch mirrors, etc.) from
     // the DB. Kept independent of TasksIslandViewModel's own handler: the row instance backing
     // Task may have been replaced by a full list reload, so this must not assume it stayed live.
+    private async System.Threading.Tasks.Task RefreshLatestRunSessionIdAsync(string taskId)
+    {
+        try
+        {
+            await using var ctx = await _dbFactory.CreateDbContextAsync();
+            var latestRun = await new TaskRunRepository(ctx).GetLatestByTaskIdAsync(taskId);
+            if (Task?.Id != taskId) return;
+            LatestRunSessionId = latestRun?.SessionId;
+        }
+        catch { /* best-effort */ }
+    }
+
     private async System.Threading.Tasks.Task RefreshBoundTaskAsync(string taskId)
     {
         try