style(ui): polish islands and remove terminal traffic-light dots

src/ClaudeDo.Ui/ViewModels/Modals/DiffModalViewModel.cs

@@ -41,6 +41,7 @@ public sealed partial class DiffModalViewModel : ViewModelBase
     private readonly GitService _git;
 
     public required string WorktreePath { get; init; }
+    public string? BaseRef { get; init; }
 
     public ObservableCollection<DiffFileViewModel> Files { get; } = new();
 
@@ -62,7 +63,12 @@ public sealed partial class DiffModalViewModel : ViewModelBase
         Files.Clear();
 
         string raw;
-        try { raw = await _git.GetDiffAsync(WorktreePath, ct); }
+        try
+        {
+            raw = BaseRef is not null
+                ? await _git.GetBranchDiffAsync(WorktreePath, BaseRef, ct)
+                : await _git.GetDiffAsync(WorktreePath, ct);
+        }
         catch { return; }
 
         if (string.IsNullOrWhiteSpace(raw)) return;