Desktop: stop the status bar's session timer when the shell ends

src/DodoSSH.Client.Shell/ViewModels/MainWindowViewModel.cs

@@ -4518,7 +4518,7 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
     {
         if (Tabs.FirstOrDefault(tab => tab.SessionId == e.SessionId) is { } tab)
         {
-            tab.Ended(e.Outcome.End, e.Outcome.Description);
+            tab.Ended(e.Outcome.End, e.Outcome.Description, clock.GetUtcNow());
 
             // Only for the tab being looked at, which is what these three already ask. The rectangle does not
             // change — a dead tab keeps its pane and its scrollback — but the status bar under it does, and
@@ -4998,7 +4998,12 @@ internal sealed partial class MainWindowViewModel : ObservableObject, IAsyncDisp
                 return null;
             }
 
-            var elapsed = clock.GetUtcNow() - started;
+            // Up to the end, for a shell that has one: how long it ran, not how long ago it started.
+            var until = Surface is ShellSurface.Terminal && SelectedTab?.EndedAt is { } ended
+                ? ended
+                : clock.GetUtcNow();
+
+            var elapsed = until - started;
 
             if (elapsed < TimeSpan.Zero)
             {