Merge branch 'main' into the Android head

Main grew the screens the host-management plan called for — hosts, pins, snippets, logs,
import, teams — plus the ObjectStore and Import projects behind two of them, and moved
WindowsDeviceKeyStore into the desktop head's Platform folder.

Five of those view models landed in a directory this branch had already moved, so they
join the rest in DodoSSH.Client.Shell: git spotted the rename and put them there, and the
namespaces followed. Shell picks up ObjectStore and Import as a result, which the Android
head then gets transitively and will use neither of at first — scoped storage means there
is no ~/.ssh/config to import, and file transfer is out of its first scope.

Desktop suites green at 155 and 64.

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

@@ -1,11 +1,14 @@
 using Avalonia;
+using Avalonia.Controls;
 using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Input.Platform;
 using Avalonia.Markup.Xaml;
-using DodoSSH.Client.Shell.Terminal;
-using DodoSSH.Client.Shell.ViewModels;
+using DodoSSH.Client.App.Platform;
 using DodoSSH.Client.App.Views;
 using DodoSSH.Client.Auth;
 using DodoSSH.Client.Session;
+using DodoSSH.Client.Shell.Terminal;
+using DodoSSH.Client.Shell.ViewModels;
 using DodoSSH.Client.Ssh;
 using DodoSSH.Client.Storage;
 using DodoSSH.Client.Terminal;
@@ -47,6 +50,28 @@ internal sealed partial class DodoSshApp : Application
     /// nowhere honest to release them.
     /// </para>
     /// </remarks>
+    /// <summary>
+    /// Puts one line of text on the system clipboard.
+    /// </summary>
+    /// <remarks>
+    /// The clipboard is reached through the window, and at composition time there is no window yet — hence
+    /// a closure that looks it up on each call rather than a reference captured now. A machine with no
+    /// clipboard falls through silently here; the view model is the one that decides what to say, and it
+    /// distinguishes "no clipboard on this machine" from "copied" because they are different answers.
+    /// <para>
+    /// A delegate rather than handing the view model an <c>IClipboard</c>, so that nothing in the view
+    /// models needs a visual and every test that drives them stays window-free.
+    /// </para>
+    /// </remarks>
+    private static Func<string, Task> ClipboardWriter(IClassicDesktopStyleApplicationLifetime desktop) =>
+        async text =>
+        {
+            if (TopLevel.GetTopLevel(desktop.MainWindow) is { Clipboard: { } clipboard })
+            {
+                await clipboard.SetTextAsync(text).ConfigureAwait(false);
+            }
+        };
+
     private static void Compose(IClassicDesktopStyleApplicationLifetime desktop)
     {
         var paths = ClientPaths.Default;
@@ -74,7 +99,7 @@ internal sealed partial class DodoSshApp : Application
         // Chosen once, here, because it is a property of the machine and not of any session. A computer with
         // a usable TPM gets the store that keeps a device key behind a Windows consent prompt; anything else
         // gets one that reports itself unavailable, so unlock keeps asking for the passphrase. See ADR 0007.
-        var deviceKeys = DeviceKeyStores.ForThisMachine(paths);
+        var deviceKeys = DesktopDeviceKeyStores.ForThisMachine(paths);
 
         var viewModel = new MainWindowViewModel(
             paths,
@@ -93,7 +118,9 @@ internal sealed partial class DodoSshApp : Application
             // makes a launch after the first one arrive online rather than merely enrolled.
             resume: async (url, refreshToken, cancellationToken) => await ServerConnection
                 .ResumeAsync(url, refreshToken, TimeProvider.System, cancellationToken)
-                .ConfigureAwait(false));
+                .ConfigureAwait(false),
+
+            copyToClipboard: ClipboardWriter(desktop));
 
         desktop.MainWindow = new MainWindow { DataContext = viewModel };