feat(ui): wire redesigned detail island (header + description/steps card + work console)

Replace the long scrolling DetailsIslandView with the new pinned layout: a
separated TaskHeaderBar (trash↔skull, gear), a DescriptionStepsCard (text⇄steps
toggle, Preview = composed prompt), and a pinned WorkConsole (Output/Actions/
Session tabs). The three components now bind to DetailsIslandViewModel; their
scaffolding sample VMs are removed. Drops the old inline sections + AgentStripView.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

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

@@ -74,8 +74,12 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
     private TaskRowViewModel? _task;
 
     // Editable fields
-    [ObservableProperty] private string _editableTitle = "";
-    [ObservableProperty] private string _editableDescription = "";
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ComposedPreview))]
+    private string _editableTitle = "";
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ComposedPreview))]
+    private string _editableDescription = "";
     [ObservableProperty] private bool _isEditingDescription;
     [ObservableProperty] private bool _isDescriptionExpanded = true;
 
@@ -100,6 +104,46 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
     [RelayCommand]
     private void ToggleDescriptionExpanded() => IsDescriptionExpanded = !IsDescriptionExpanded;
 
+    // ── Description/Steps card (redesign) ──────────────────────────────
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(IsDescriptionView))]
+    private bool _isStepsView;
+
+    public bool IsDescriptionView => !IsStepsView;
+
+    [RelayCommand]
+    private void ToggleCardView() => IsStepsView = !IsStepsView;
+
+    // The exact text handed to Claude: title + description + open steps only.
+    public string ComposedPreview =>
+        ClaudeDo.Data.TaskPromptComposer.Compose(
+            EditableTitle, EditableDescription, Subtasks.Select(s => (s.Title, s.Done)));
+
+    // ── Work console (redesign) ────────────────────────────────────────
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(IsOutputTab))]
+    [NotifyPropertyChangedFor(nameof(IsActionsTab))]
+    [NotifyPropertyChangedFor(nameof(IsSessionTab))]
+    private string _selectedTab = "output";
+
+    public bool IsOutputTab  => SelectedTab == "output";
+    public bool IsActionsTab => SelectedTab == "actions";
+    public bool IsSessionTab => SelectedTab == "session";
+
+    [RelayCommand]
+    private void SelectTab(string? tab) => SelectedTab = tab ?? "output";
+
+    public string TurnsText   => $"{Turns} turns";
+    public string DiffAddText => $"+{DiffAdditions}";
+    public string DiffDelText => $"-{DiffDeletions}";
+
+    public bool ShowRoadblock => IsFailed || IsCancelled;
+    public string RoadblockMessage =>
+        IsFailed ? "The session ended with an error." :
+        IsCancelled ? "The session was cancelled." : "";
+
+    public string SessionLabel => "claude-session";
+
     // Short task-id badge, e.g. "#T1A"
     public string TaskIdBadge => Task != null ? $"#T{Task.Id[..Math.Min(3, Task.Id.Length)].ToUpperInvariant()}" : "";
 
@@ -142,6 +186,8 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
         OnPropertyChanged(nameof(ShowContinue));
         OnPropertyChanged(nameof(ShowResetAndRetry));
         OnPropertyChanged(nameof(IsAgentSectionEnabled));
+        OnPropertyChanged(nameof(ShowRoadblock));
+        OnPropertyChanged(nameof(RoadblockMessage));
     }
     [ObservableProperty] private string? _model;
 
@@ -221,8 +267,9 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
     public string ElapsedFormatted => "";  // placeholder — no start-time stored yet
 
     partial void OnTokensChanged(int value)   => OnPropertyChanged(nameof(TokensFormatted));
-    partial void OnDiffAdditionsChanged(int value) => OnPropertyChanged(nameof(DiffMeterRatio));
-    partial void OnDiffDeletionsChanged(int value) => OnPropertyChanged(nameof(DiffMeterRatio));
+    partial void OnTurnsChanged(int value)    => OnPropertyChanged(nameof(TurnsText));
+    partial void OnDiffAdditionsChanged(int value) { OnPropertyChanged(nameof(DiffMeterRatio)); OnPropertyChanged(nameof(DiffAddText)); }
+    partial void OnDiffDeletionsChanged(int value) { OnPropertyChanged(nameof(DiffMeterRatio)); OnPropertyChanged(nameof(DiffDelText)); }
 
     // 0.0–1.0 additions share for the diff meter
     public double DiffMeterRatio
@@ -328,6 +375,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
         _services = services;
         _notesApi = notesApi;
         Notes = new NotesEditorViewModel(_notesApi);
+        Subtasks.CollectionChanged += (_, _) => OnPropertyChanged(nameof(ComposedPreview));
         Loc.LanguageChanged += (_, _) =>
         {
             OnPropertyChanged(nameof(AgentStatusLabel));
@@ -1092,6 +1140,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
     {
         if (row is null) return;
         row.Done = !row.Done;
+        OnPropertyChanged(nameof(ComposedPreview));
         await using var ctx = _dbFactory.CreateDbContext();
         var repo = new SubtaskRepository(ctx);
         var subs = await repo.GetByTaskIdAsync(Task?.Id ?? "");
@@ -1157,6 +1206,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
             await repo.UpdateAsync(entity);
         }
         row.Title = title;
+        OnPropertyChanged(nameof(ComposedPreview));
     }
 
     [RelayCommand]