Give the application a settings area built from what really exists

src/DodoSSH.Client.App/Views/SettingsAccountPage.axaml.cs

@@ -0,0 +1,9 @@
+using Avalonia.Controls;
+
+namespace DodoSSH.Client.App.Views;
+
+/// <summary>Settings mode's Account page: the read-only profile, the sign-in fact, and signing out.</summary>
+internal sealed partial class SettingsAccountPage : UserControl
+{
+    public SettingsAccountPage() => InitializeComponent();
+}