feat(ui): add Restore default agents button to Settings modal

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

@@ -161,6 +161,32 @@ public sealed partial class SettingsModalViewModel : ViewModelBase
         finally { IsBusy = false; }
     }
 
+    [RelayCommand]
+    private async Task RestoreDefaultAgents()
+    {
+        IsBusy = true;
+        StatusMessage = "";
+        try
+        {
+            var result = await _worker.RestoreDefaultAgentsAsync();
+            if (result is null)
+                StatusMessage = "Worker offline.";
+            else if (result.Copied == 0 && result.Skipped == 0)
+                StatusMessage = "No default agents bundled.";
+            else if (result.Copied == 0)
+                StatusMessage = "All default agents already present.";
+            else
+                StatusMessage = $"Restored {result.Copied} default agent(s).";
+
+            await _worker.RefreshAgentsAsync();
+        }
+        catch (Exception ex)
+        {
+            StatusMessage = $"Restore failed: {ex.Message}";
+        }
+        finally { IsBusy = false; }
+    }
+
     [RelayCommand]
     private void OpenPath(string? path)
     {

src/ClaudeDo.Ui/Views/Modals/SettingsModalView.axaml

@@ -184,6 +184,23 @@
             </Border>
           </StackPanel>
 
+          <!-- AGENTS -->
+          <StackPanel Spacing="0">
+            <TextBlock Classes="section-label" Text="AGENTS"/>
+            <Border Classes="section">
+              <StackPanel Spacing="8">
+                <TextBlock Text="Restore bundled default agents (code-reviewer, test-writer, debugger, security-reviewer, explorer, researcher). Existing files are not overwritten."
+                           FontSize="11"
+                           TextWrapping="Wrap"
+                           Foreground="{DynamicResource TextDimBrush}"/>
+                <Button Content="Restore default agents"
+                        Command="{Binding RestoreDefaultAgentsCommand}"
+                        IsEnabled="{Binding !IsBusy}"
+                        HorizontalAlignment="Left"/>
+              </StackPanel>
+            </Border>
+          </StackPanel>
+
           <!-- ABOUT -->
           <StackPanel Spacing="0">
             <TextBlock Classes="section-label" Text="ABOUT"/>